Dry paint transfer product having high DOI automotive paint coat

ABSTRACT

An automotive quality paint coat is laminated to the exterior surface of a molded plastic car body member or panel. In one embodiment, the paint coat includes an exterior clear coat above a color coat. During processing, the clear coat and color coat are each coated on a temporary flexible casting sheet and dried. A high gloss surface is transferred to the clear coat from the casting sheet. The paint coat is then transferred from the casting sheet to a thin, semi-flexible thermoformable plastic backing sheet by dry paint transfer-laminating techniques. The resulting laminate is thermoformed into a complex three-dimensional shape of the car body member or panel. The preformed laminate is then bonded to an underlying plastic substrate material, by injection-cladding techniques, for example, to form the finished article. The paint coat has sufficient elongation to retain exterior automotive appearance and durability properties during thermoforming without deglossing. The backing sheet absorbs defects in the substrate material so the paint coat retains its appearance and durability properties during the injection-cladding step. The finished article comprises a high gloss, defect-free paint coat on the exterior of a molded plastic car body member or panel. Solution-form polyvinylidene fluoride/acrylic paint systems have remarkably high combined gloss and distinctiveness-of-image levels, together with durability properties required for exterior automotive use.

This is a division of Ser. No. 08/265,685 filed Jun. 24, 1994 and nowabandoned, which in turn is a continuation of Ser. No. 07/712,135 filedJun. 3, 1991, now abandoned, which in turn is a division of Ser. No.07/424,302 filed Nov. 22, 1989, now abandoned, which in turn is acontinuation-in-part of Ser. No. 07/162,917 filed Mar. 2, 1988, nowabandoned, which in turn is a continuation-in-part of Ser. No. 031,984filed Mar. 27, 1987, now abandoned.

FIELD OF THE INVENTION

This invention relates generally to dry paint transfer techniques, andmore particularly to the use of these techniques to produce exteriorplastic car body members or panels with a paint coat applied in aseparate production operation which can eliminate or greatly reduce thepainting steps carried out in the manufacturing operations of aconventional automobile production plant.

BACKGROUND

Automotive design and manufacture present a unique set of problems inthe selection of materials and processes used in the manufacture ofautomobile bodies. As a form of transportation, automobiles are uniquebecause most buyers want a vehicle to have a certain individual styling.A recent trend in the automobile industry is toward production ofdistinctive vehicles styled to attract specific groups of consumers.This change has required the car builder to shift production from a fewmodels manufactured in large volumes to a larger number of moredistinctive body styles. These developments have demanded from themanufacturer both styling flexibility and reasonable tooling costs foreach body style.

For many years, car body members and panels have been made predominantlyfrom sheet metal. However, car builders now generally recognize thatfuture use of plastics for exterior car body members and panels, ratherthan sheet metal, may provide a solution to meeting the demand for moreunique body styling and reduced tooling costs. With the increasingconcern for weight-reduction, car builders have also turned theirattention to the use of plastics as an alternative to heavier metalparts. For instance, certain exterior car body parts of many automobilesnow on the road are made from lighter-weight plastic. These partsinclude bumpers, rocker panels, fender extensions, window and doormoldings, and the like.

As reported in Plastics World, November, 1986, p. 30 et seq., a numberof advanced corporate development program now in process are alsoseeking solutions to the problem of commercially manufacturing fromplastics the larger exterior car body panels such as hoods, roofs, decklids, and in fact, the entire car body, if possible. The concept ofmaking a production car body from a material other than sheet metaldates back to at least as early as the mid-1950's, when the ChevroletCorvette was first manufactured with a fiberglass body. Developments inplastic resin technology in recent years have resulted in moresophisticated plastic materials of higher impact strength thanfiberglass. Polycarbonates are an example. These developments inplastics technology have caused many plastics manufacturers, for aboutthe last decade or so, to seek solutions to the problem of commerciallyproducing the entire car body at a reasonable cost from theselater-developed high-strength plastic materials. Recent developmentefforts have also been directed toward producing plastic car bodies fromvarious alternative plastics molding processes, including use of SMC(sheet molding compounds) and RIM (reaction injection molding)techniques.

Development of a production process for making exterior car body membersand panels from plastics requires solutions to a number of technicalproblems. These parts must be manufactured at reasonable costs fortooling, assembly and materials. The end product also must meet certainquality requirements. For instance, the resulting car body panel musthave structural capabilities such as impact strength and resistance tomechanical stress necessary to compete with sheet metal. It must alsohave a paint coat with a defect-free and durable exterior surface. Anautomotive quality paint coat must meet certain specifications for alarge number of physical properties in order to be capable of use as anexterior automotive paint coat. These properties include gloss;distinctiveness-of-image; hardness; abrasion resistance; weatherabilitysuch as UV resistance; impact strength; thermal stability, namely,resistance to extreme high and low temperatures; gasoline and acidresistance; cleanability; adhesion to the underlying car body panel;resistance to water and humidity exposure; and hiding ability or opacityof the paint coat.

In the past, a conventional production process for applying an exteriorpaint coat to car bodies made of sheet metal has involved transportingthe preformed auto bodies to application lines in the plant where thecar bodies are dipped in paint, followed by transporting them to aseparate location for baking the paint coat and waiting until thehardened paint coat dries thoroughly. Most paint systems today areacrylic enamels which are cross-linked into a hard, glossy, durablepaint coat during baking. Following painting, the car bodies aretransported back to the production plant for further assemblyoperations. The painting of plastic car body members has typicallyinvolved manually spray painting the plastic parts in a separatepainting facility, followed by drying, and then transporting thefinished parts back to the assembly operation. Conventional painting ofsheet metal car bodies and plastic parts is expensive and is asignificant factory problem with respect to environmental protection,workers' safety, corrosion treatment, and waste disposal. It isestimated that about one third of the total capital investment in anautomobile production facility today is involved in painting car bodymembers and panels.

In recent years, metalized laminating techniques have been used forforming a reflective, weather-resistant metal surface on molded plasticautomotive trim parts. These techniques have not yielded plastic trimparts with a paint-coated surface capable of exterior automotive use.Such plastic trim parts have experienced difficulties in maintainingreflectivity and avoiding surface defects under mechanical impact andenvironmental exposure.

New car body applications of molded plastic materials can develop if themanufacturer can find a way to commercially produce plastic car bodypanels with a paint coat having the durability and appearance propertiesnecessary for exterior automotive use. Moreover, if in-mold painting orcoating processes can be developed as an alternative to conventionalauto painting, then auto assembly plants can be more compact, andcapital costs and environmental and safety problems associated withconventional car painting at the factory site can be avoided.

Many corporate product development efforts have sought alternatives toconventional painting of molded plastic exterior car body panels andparts, but without any known success to date. A number of problems mustbe overcome to develop an economical production-type paint system andprocess for applying a paint coat capable of exterior automotive use formolded plastic exterior car body panels and parts so as to eliminateconventional spray painting operations. For instance, use of thecross-linked acrylic enamel paint systems which are commonly baked onthe sheet metal car bodies to produce a tough, glossy finish cannot beused in painting plastic car bodies because of temperature limitations.One approach, which is the subject of this invention, involvesdeveloping a paint-coated laminate which can be used to replace theconventional painted finish on the exterior of an automobile body. Thelaminate is made from a paint coat applied to a casting sheet by paintcoating techniques. The dried paint coat is then transferred from thecasting sheet to a laminate panel by dry paint transfer techniques. Thecoating operation permits use of high temperature resistant paintsystems capable of producing a tough, glossy finish. The laminate islater thermoformed into a complex three-dimensional shape and thenbonded or integrally molded to an underlying plastic car body member orpanel. Injection-cladding techniques can be used to manufacture a moldedplastic part and simultaneously bond the laminate to the exterior of themolded plastic part.

A number of technical problems must be overcome in order to use such alaminate in a thermoforming and injection-cladding process, whilemaintaining a defect-free painted surface with high gloss and durabilityproperties throughout the thermoforming and injection-cladding steps.For instance, the laminate must be heat and vacuum-formable into acomplex three-dimensional shape without cracking, deglossing, stresswhitening or creating other surface defects. A paint coat on such alaminate can require a substantial amount of pigment in order to providethe necessary color density or opacity and distinctiveness-of-image.However, it has been found that use of pigments in a paint coat cancause deglossing of the surface when a paint-coated laminate isthermoformed. Deglossing may even occur in a nonpigmented clear coatduring thermoforming.

In addition to surface gloss requirements, the finished paint coat mustbe defect-free. Defects must not be produced by the thermoforming step,and the laminate also must be bonded or molded to the underlying plasticsubstrate in a manner that hides any defects that may be present in thesubstrate material.

Moreover, a finished paint coat may have a reasonably high surfacegloss, but still not have the desired visual appearance known asdistinctiveness-of-image. This property relates to the mirror-likecharacter of the finish and is measured by the clarity of an imagereflected by the finished surface. It is difficult, in a thermoformingoperation, to produce an exterior automotive paint coat with a highgloss level and a high distinctiveness-of-image.

Durability properties are also critical in producing a paint coatcapable of exterior automotive use. The paint coat must avoid exhibitingdefects when exposed to mechanical impact and avoid deterioration of thesurface from exposure to chemicals and to the weather.

A paint system that produces the toughness or hardness necessary forexterior automotive use also must have the elongation properties andheat resistance necessary to allow thermoforming of the paint coat intocomplex three-dimensional shapes without cracking, deglossing, producingstress lines or other surface non-uniformities, or otherwise degradingthe finish. Large pigment levels also adversely affect the strength andalter elongation properties of the paint coat. In addition, reliablebonding of the paint coat to the laminate and bonding of the laminate tothe underlying substrate material are essential.

Thus, the desired paint system should have a critical combination ofmany physical properties in order to produce a surface capable ofexterior automotive use, while retaining desired surface characteristicsafter the laminating, thermoforming and injection-cladding or moldingsteps have been carried out. However, some physical properties tend tobe mutually incompatible in such a process. For instance, a paint systemmay have good qualities of durability such as hardness, toughness,weatherability and the like; but the same paint system may not havesufficient elongation to be heat-formed into a complex shape withoutcracking or otherwise losing its durability properties. Other paintsystems may degloss when heat-formed into a complex shape. Some paintsystems have sufficient elongation to permit thermoforming into thedesired complex shape, but they are too soft and therefore lacking inthe necessary hardness or durability properties.

In summary, there is a need for an economical production process formanufacturing highly contoured molded plastic exterior car body membersor panels with a laminated paint coat having both the durability and thegloss and other appearance properties sufficient for exterior automotiveuse. Laminating techniques for applying a paint coat to such a moldedplastic part can provide a valuable alternative to conventional paintingof exterior car body members. Certain properties, such as glass-smooth,defect-free surfaces and uniform paint coats, are better produced bylaminating techniques than by conventional painting. Capital costs alsocan be reduced and environmental problems can be alleviated. Laminatingtechniques require, in addition, however, a paint system and processingtechniques capable of producing and maintaining, throughout processing,the durability and elongation properties, opacity, gloss anddistinctiveness-of-image levels, and defect-free surface necessary forexterior automotive applications. The present invention solves theseproblems.

SUMMARY OF THE INVENTION

Briefly, one embodiment of this invention provides a process formanufacturing a molded plastic article having a finished paint coat withsurface properties meeting criteria for exterior automotive use. Theseinclude properties providing predetermined durability, gloss and otherappearance characteristics in the finished paint coat. In this process,the paint coat is applied to a three-dimensionally shaped exteriorsurface of an intermediate laminate by a combination of paint coating,dry paint transfer-laminating, and thermoforming techniques. Thethermoformed laminate then can be bonded to or molded to an underlyingplastic substrate, for example, by injection-cladding techniques, withthe paint coat maintaining properties sufficient for exterior automotiveuse throughout these processing steps. The invention is described hereinin the context of a paint coat applied to the surface of a plastic carbody member or panel, but the invention is also applicable to otherarticles of manufacture having a paint coat with properties similar tothose required for exterior automotive use.

Considering the application of the invention to a process for making aplastic exterior car body panel, a paint coat comprising a syntheticresinous material is coated in thin-film form onto a flexible,heat-resistant temporary casting sheet. The paint coat is dried on thesheet sufficiently to harden it and transfer a predetermined exteriorsurface gloss level from the casting sheet to the paint coat. The paintcoat may comprise a clear coat and a separate pigmented color coat. Theclear coat and color coat may be formed as separate thin-film coatingswhich are dried and then bonded to one another. The color coat, incombination with the clear coat, provides a composite paint coat havingthe durability, gloss and other appearance properties necessary forexterior automotive use. The paint coat is transferred to a semirigid,thermoformable synthetic resinous backing sheet so that the paint coatprovides the exterior surface of the paint-coated backing sheet. Thelaminate formed by the backing sheet and the bonded paint coat isthereafter thermoformed to produce a three-dimensionally shapedpreformed laminate, while still retaining durability, gloss and otherappearance properties necessary for exterior automotive applications.The thermoforming step can produce substantial elongation of the paintcoat. The paint coat is capable of elongating from about 50% to about150%, or more, during thermoforming, without significant loss of itsexterior automotive durability, gloss and other appearance properties.In a subsequent injection-cladding step, for example, a syntheticresinous substrate material is injection molded behind the preformedpaint-coated laminate to bond the laminate to the substrate. This formsa molded plastic article with a painted surface which retains theexterior automotive surface characteristics. The substrate can be anexterior body panel of a motor vehicle. The substrate material normallymay have a substandard surface finish, but the backing sheet absorbssurface defects in the substrate material during the injection-claddingstep so as to retain the minimum surface defect level and gloss requiredof an exterior automotive paint coat.

In one embodiment, the paint coat comprises a fluorinated polymer andacrylic resin-containing paint system with thermoplastic properties. Therelative amounts of the fluorinated polymer and acrylic resin componentsin the paint coat formulation provide a sufficient level of resistanceto deglossing and sufficient elongation for the laminate to bethermoformed into complex three-dimensional shapes while providingsufficient durability and appearance properties for the finished productto be useful as an exterior automotive body member or panel.

In one embodiment in which the paint coat comprises an exterior clearcoat and an underlying color coat bonded to the clear coat, the clearcoat can be formed from a fluorinated polymer and acrylicresin-containing coating. In this case, the clear coat can provide themajority of the durability, gloss and other appearance propertiesnecessary for use as an exterior automotive paint coat. The color coatalso can comprise a thermoplastic fluorinated polymer and acrylicresin-containing paint system. Other paint systems compatible with theclear coat and the backing sheet also can be used.

In one form of the invention, the fluorinated polymer componentcomprises polyvinylidene fluoride (PVDF), and the acrylic resincomponent can be a polymethyl methacrylate resin, a polyethylmethacrylate resin, or mixtures thereof, including copolymers thereof.One finished product having a surface capable of exterior automotive useis made from a paint system comprising from about 50% to about 70% PVDFand from about 30% to about 50% acrylic resin, by weight of the totalPVDF and acrylic solids, exclusive of the pigment.

This invention also provides an exterior automotive quality paint coathaving unusually high gloss and distinctiveness-of-image (DOI) alongwith other durability properties sufficient for exterior automotive use.This embodiment of the invention includes a thermoformable laminatehaving a paint coat bonded to it in which the paint coat, prior tocasting on a casting sheet, was prepared as a solution of vinylidenefluoride in acrylic resin. The paint coat comprises at least a clearcoat of vinylidene fluoride and acrylic resin coated from solution,which produces thermoformed laminates with high combined gloss and DOIlevels. Good combined gloss and DOI levels have been obtainedexperimentally when the clear coat and pigmented base coat both areprepared as a solution of vinylidene fluoride in the acrylic resin. Inone experimental test of a finished car body panel, a 60° gloss level ofgreater than about 75 gloss units and a DOI approaching about 90 unitswere achieved.

Different forms of the invention are disclosed herein. One embodimentcomprises a thermoformable laminate having a paint coat with propertiescapable of use in forming an exterior automotive finish on a plasticexterior car body panel. A further embodiment of the invention providesa process for applying a paint coat to an exterior body panel of a motorvehicle so that the paint coat in its finished form has the durability,gloss and other appearance properties necessary for exterior automotiveuse. Another embodiment of the invention comprises a pressure-sensitiveadhesive-backed paint-coated laminate capable of use in automotive paintcoat repair.

Thus, the present invention provides a process and articles ofmanufacture in which a laminated exterior paint coat ultimately forms anexterior finish on a highly contoured surface of a molded plasticarticle. The paint coat has a sufficient combination of elongation andresistance to deglossing to withstand thermoforming without disruptingthe high gloss surface originally present, while retaining thedurability and appearance properties sufficient to be useful as anexterior paint coat for a plastic car body panel.

These and other aspects of the invention will be more fully understoodby referring to the following detailed description and the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a semi-schematic perspective view illustrating an automobilewhich may have one or more of its exterior body members or panels madefrom a molded plastic substrate having a paint coat produced accordingto principles of this invention.

FIG. 2 is a front elevation view illustrating a rear window panelsection of a motor vehicle in which an exterior paint coat is formed onthe surface of the window panel according to principles of thisinvention.

FIG. 3 is a cross-section taken on line 3--3 of FIG. 2 for illustratingthe complex three-dimensional shape of the paint coat transferred to theexterior surface of the window panel.

FIG. 4 is a schematic cross-sectional view illustrating one embodimentof a paint-coated carrier sheet used in the dry painttransfer-laminating steps of this invention. Film thicknesses areexaggerated in size and not to scale, for simplicity.

FIG. 5 is a schematic side elevation view illustrating a paint coatingstep of the process.

FIG. 6 is a schematic side elevation view illustrating a laminating stepof the process.

FIG. 7 is a schematic cross-sectional view illustrating a dry compositepaint coat transferred to a backing sheet during the laminating step.Film thicknesses are exaggerated in size and not to scale, forsimplicity.

FIG. 8 is a schematic view illustrating a thermoforming step of theprocess in which a paint-coated laminate is heated prior to vacuumforming.

FIG. 9 is a schematic view illustrating another thermoforming step inthe process.

FIG. 10 is a schematic cross-sectional view illustrating a preliminarystep in an injection-cladding step of the process.

FIG. 11 is a schematic cross-sectional view illustrating a substratematerial injection-molded behind the thermoformed laminate in aninjection mold.

FIG. 12 is schematic cross-sectional view illustrating the compositecross-sectional structure of the finished molded plastic article havingexterior paint coat. Film thicknesses are exaggerated in size and not toscale, for simplicity.

FIG. 13 is a graph illustrating a general relationship between surfacegloss and the relative amounts of polyvinylidene fluoride and acrylicresin contained in one embodiment of the paint coat.

FIG. 14 is a schematic cross-sectional view illustrating one embodimentof a laminate having a dry paint film and a pressure-sensitive adhesivebacking for use in automotive paint coat repair, according to principlesof this invention.

DETAILED DESCRIPTION

A paint coat with a surface capable of exterior automotive use isapplied to a molded plastic article by a combination of paint coating,dry paint transfer-laminating, and thermoforming techniques for forminga paint-coated laminate which is then bonded to or molded to anunderlying plastic substrate. The thermoformed laminate can be bonded tothe substrate by injection-cladding techniques. The exterior automotiveproperties of durability, gloss and other appearance criteria areproduced and maintained throughout the process.

FIGS. 1 through 3 illustrate one embodiment of the dry paint transferprocess and product in which an exterior automotive paint coat istransferred to an exterior body member or panel of an automobile 20. Inthe illustrated embodiment, the paint coat is transferred to theexterior surface of a rear window panel or molding 22 of the vehicle.The rear window molding can be injection-molded from a wood-filledsynthetic resinous plastic substrate 24 which forms the structuralportion of the panel. The paint coat 26 can be transferred to theexterior surface of the substrate by the paint coating, dry painttransfer-laminating, thermoforming and injection-cladding techniquesdescribed below. The paint coat 26 has properties useful in an exteriorautomotive paint coat, and these properties are also described in moredetail below. Use of the process and article of this invention isdescribed in the context of exterior car body members and panels,although other end uses of the process and article also are possible,without departing from the scope of the invention. For simplicity,exterior car body members or panels are referred to herein as car bodypanels.

The plastic substrate material 24 can contain large amounts of fillermaterials which can produce a normally substandard surface on thesubstrate. In carrying out the invention, the paint coat 26 istransferred to the surface of the substrate so that any imperfections inthe underlying structural surface are absorbed by the laminate, thuspresenting a perfectly smooth, unblemished paint coat having propertiessufficient for exterior automotive uses. The rear window molding servesas an example of the type of highly contoured exterior surface to whichthe paint coat can be transferred. Referring to the rear window molding22 in FIGS. 2 and 3, the molding has a large oblong-shaped windowopening 28 with a wide border 30 having a highly contoured exteriorsurface extending around the window opening. The complexly shaped,multiple contour surface includes a curved outer ridge 32 of taperedcross-section extending around the periphery of the molding, alongitudinally curved and narrow recessed region 34 extending inside theouter ridge, and a wide border section 36 of raised elevation inside therecessed region 34 extending around the entire periphery of the windowopening. The wide border region 36 is at the same elevation as thesurface of a wide end member 38 at one of the window opening. An insideedge 40 of the wide border section 36 has a tapered cross-sectionalthickness and extends around the inside of the window opening. Asrepresented in FIGS. 2 and 3, the exterior automotive paint coat 26 isadhered to the complexly shaped exterior surface of the rear windowmolding, but the paint coat also can provide a durable, high glossexterior surface useful on other car body panels of various irregularlyshaped three-dimensional surface configurations, as well as otherarticles of manufacture.

Paint Coat

The process first includes the step of coating a paint coat, or aportion of a paint coat, onto one or more temporary carrier sheets. FIG.4 illustrates one embodiment of a paint-coated carrier 41 whichincludes, in combination, a flexible, foldable, heat-resistant,self-supporting carrier sheet 42, also referred to in the art as acasting film; and a transferable, adherent, flexible paint coat 44coated onto one surface of the carrier. The paint coat 44 is anon-self-supporting, flexible synthetic resinous dry film-form coating.The paint coat 44 can comprise a combination exterior clear coat and acolor coat, or a combination exterior clear coat and a tint coat; or thepaint coat may comprise a single dry film-form coating of a pigmentedsynthetic resinous material having the exterior automotive propertiesdescribed below. In a presently preferred form, the paint coat 44includes a clear coat 45 coated over the carrier and dried, and a colorcoat 46 on the dried clear coat. The color coat can be coated onto thedried clear coat. Alternatively, the clear coat and the color coat canbe separately coated onto corresponding carrier sheets and dried ontheir respective carriers. The color coat then can be later bonded tothe clear coat. The combination clear coat and color coat are referredto herein as the paint coat 44, or a composite paint coat, forsimplicity.

The paint-coated carrier also optionally can include a size coat 47coated on the dried color coat. The size coat provides adhesion to abacking sheet in a subsequent laminating step. In one embodiment,described below, a thermoplastic polyolefin backing sheet is used, and athermoplastic chlorinated polyolefin size coat provides superioradhesion between the paint coat and the backing sheet.

The carrier sheet 42 is preferably a polyester casting film having ahigh gloss surface 48. The carrier can be a polyester film such as Mylar(a trademark of DuPont), American Hoechst 3000 polyester film, or thelike. The preferred film thickness of the carrier sheet is about twomils. Polyester films are preferred because the high gloss surface 48 iscapable of transferring a high gloss level to a surface 49 of the clearcoat 45 in contact with the carrier, where the transferred gloss levelis sufficient for exterior automotive use. Alternatively, the coatingscan be cast on a polished metal belt. If the color coat is cast on aseparate carrier sheet, the surface gloss imparted to the color coatfrom the carrier is not critical. The polyester carrier film has asufficiently high heat resistance to resist axial elongation under thetemperatures applied during subsequent paint coat drying and laminatingsteps. The clear coat may be applied to the polyester carrier filmwithout a release coat on the high gloss surface 48 of the carrier. Thiscan avoid a separate coating, which might detrimentally affect transferof the high gloss surface from the carrier to the surface 49 of theclear coat. The formulation of the clear coat is such that the clearcoat can be easily transferred from the carrier sheet and can replicatethe high gloss surface of the carrier after the clear coat dries andafter subsequent dry paint transfer-laminating steps in which the paintcoat is transferred from the carrier to a laminate described below.

As an optional step, a thin film of wax (not shown) can be coated ontothe carrier sheet and dried, followed by coating the clear coat 45 overthe thin film of wax. The wax is coated in a film thickness (less than0.01 mil and preferably 0.001 mil) that avoids any adverse effect on theclear coat replicating the surface gloss of the carrier.

The clear coat 45 is a transparent or substantially transparentthermoplastic synthetic resinous coating composition coated in thin-filmform onto the surface of the carrier sheet in a liquid state. Heat islater applied to the clear coat to dry it, without cross-linking theresin, while the clear coat is on the carrier. The preferred dry filmthickness of the clear coat is about 0.5 to about 1.5 mils. Preferably,the clear coat is coated onto the carrier sheet by a reverse rollcoating process illustrated in FIG. 5, although the clear coat can beapplied by gravure printing, or other conventional coating techniques.Referring to the reverse roller coating process of FIG. 5, the clearcoat lacquer 46 is contained in a coating pan 50 having a lacquer inlet52 in the main portion of the pan and a lacquer drain 54 on an oppositeside of a weir 56. An applicator roll 58 rotates to pick up the lacquerfrom the pan and coat it onto a previously uncoated polyester film 42which passes over a guide roll 60 and then passes between the applicatorroll and a rubber backup roll 62. A metering roll 64 adjacent theapplicator roll rotates in the same direction as the applicator roll. Adoctor blade 66 wipes the surface of the metering roll to properlycontrol the thickness of the coating on the applicator roll. Theadjustable gap between the metering roll and the applicator rollcontrols the thickness of the coating on the surface of the applicatorroll. The coating picked up by the applicator roll is then coated ontothe polyester film 42 as the film passes into contact with thereverse-rotating applicator roll. The applied coating on the film isshown at 68. The coated film then passes to a drying oven.

The clear coat is dried at oven temperatures in the range from about250° F. to about 400° F. Preferably, the clear coat is dried in multiplezones spaced apart along the long axis of the paint-coated carrier, inline with the reverse roll coater. A preferred drying technique involvesuse of three heating zones, with a progressively higher temperatureapplied in each successive zone. The solvent gases contained in theclear coat are essentially all driven off in the multi-stage dryingprocess. The same multi-stage drying process is used for drying thecolor coat 46 and size coat 47. The polyester carrier is resistant toheat at temperatures greater than about 450° F., so the carrier does notdeform during the drying step. The polyester carrier film thickness ofabout two mils assists the film in resisting elongation during thedrying steps. This ensures a high gloss level being replicated by thesurface 49 of the dried clear coat from the high gloss surface 48 of thecarrier. This also makes it possible to use high temperature-resistant,high gloss paint systems which cannot be applied to and dried on plasticsubstrates directly because of temperature limitations of the plasticmaterials.

The clear coat formulation produces a dry film-form exterior film which,in combination with the underlying color coat, produces a compositepaint coat having properties useful as an exterior automotive paintcoat. Such a paint coat is principally characterized by a combination ofexterior automotive durability properties and gloss and other appearanceproperties of the finished paint coat. The specifications for a paintcoat for exterior automotive use, as defined herein, include themechanical properties of hardness; abrasion resistance; thermalstability, including heat resistance; resistance to gasoline and acids;cleanability; adhesion; certain weatherability properties such as UVresistance and resistance to water and humidity exposure; and impactstrength. For simplicity, these properties are referred to collectivelyherein as "durability properties".

Weatherability, which is measured, in part, by UV resistance properties,is a durability property commonly used in the art to define standardsfor an exterior automotive paint coat. To measure UV resistance canrequire long-term exposure testing of the paint coat, for a period oftwo years in one test method. Certain long-term UV tests of the paintcoat of this invention have not been completed to date, but othershort-term accelerated UV resistance and weatherability tests of thepaint coat have been completed and are described below.

In addition to durability properties, the specifications for an exteriorautomotive quality paint coat also include tests to measure the visualappearance qualities of the finished surface. These criteria includegloss, distinctiveness-of-image (DOI), dry film thickness and hidingability or opacity of the paint coat. These properties are referred tocollectively herein as "gloss and other appearance properties".

Thus, a paint coat can have a combination of predetermined physicalproperties that collectively define whether the paint coat is capable ofuse as an exterior automotive paint finish. Generally, the paint coat ofthis invention, in dry film-form, provides a combination of theabove-described durability and appearance properties, including gloss,which enables the paint coat to function as an exterior automotive paintcoat.

The criteria used to define whether a paint coat is sufficient forexterior automotive use are not uniform throughout the automobileindustry. Certain standards can vary from one auto manufacturer to thenext, and from one car model to the next for a given auto manufacturer.Most criteria used to define an exterior automotive quality surface forthe process of this invention have been adopted from specifications andtest methods used in certain General Motors Fiero and Pontiac Grand AMtest programs. These criteria are disclosed herein as an example oftechniques that can be used to measure whether a paint coat hassufficient properties for exterior automotive use, although othercombinations of test criteria and test methods can also be used for thispurpose. The specifications and test methods for measuring theproperties of the exterior automotive paint coat of this invention aredescribed in detail below.

In addition to the properties of durability and appearance, the clearcoat formulation also imparts to the composite paint coat sufficientelongation at thermoforming temperatures to enable the paint coat to bethermoformed into complex three-dimensional shapes without deglossing ofthe clear coat and without reducing any durability property below thatrequired for an exterior automotive surface. In one embodiment, thepaint coat is thermoformed at temperatures from about 280° F. to about450° F. A laminate having the clear coat as its exterior surface iscapable of being thermoformed at these temperatures while maintainingthe durability and appearance properties of the composite paint coat.Elongation of the paint coat can be substantial when forming the complexthree-dimensional shapes of the finished article. Elongation of theclear coat (and the composite paint coat) can be greater than about 50%,and often greater than 100%, to form a highly contoured finishedarticle. Plastic car body members and panels often require such deepdraw forming. The clear coat also is capable of maintaining thedurability and appearance properties of the paint coat during asubsequent injection molding step.

The clear coat is formulated from a transparent thermoplastic(non-cross-linked) synthetic resinous coating composition. Thethermoplastic properties allow the clear coat, in dry film-form, tosoften and deform and be vacuum-formable at thermoforming temperatures,while still retaining exterior automotive durability properties, glossand other appearance properties after the heated and three-dimensionallyshaped film-form coating returns to its stable or hardened condition. Indry film-form, the clear coat has an extensibility in the range fromabout 40% to about 150% or more, at a film thickness from about 0.5 toabout 1.5 mils, and at thermoforming temperatures from about 280° F. toabout 450° F.

In one embodiment, the clear coat comprises a blend of a thermoplasticfluorinated polymer and an acrylic resin. The clear coat preferablycontains the fluorinated polymer and acrylic resin as its principalcomponents. The fluorinated polymer component is preferably athermoplastic fluorocarbon such as polyvinylidene fluoride (PVDF). Thefluorinated polymer also can include copolymers and terpolymers ofvinylidene fluoride. One thermoplastic fluorocarbon useful in the clearcoat is the polyvinylidene fluoride known as Kynar, a trademark ofPennwalt Corp. This polymer is a high molecular weight (400,000) polymerwhich provides a useful blend of durability and chemical resistanceproperties. Generally, a high molecular weight PVDF resin, with a weightaverage molecular weight of about 200,000 to about 600,000 is used.

The acrylic resin component of the clear coat can be a polymethylmethacrylate, or a polyethyl methacrylate resin, or mixtures thereof,including methacrylate copolymer resins, and minor amounts of othercomonomers. The clear coat also can include minor amounts of blockcopolymers and/or compatibilizers to stabilize the blended PVDF andacrylic resin system and provide compatibility between films.

In one embodiment, a principal component of the acrylic resin containedin the clear coat is a medium molecular weight polymethyl methacrylateresin such as Elvacite 2010, a trademark of DuPont. (In all furtherreferences to Elvacite resins herein, it should be noted that Elvaciteis a trademark of DuPont for a group of its acrylic resins.) In anotherembodiment, a principal component of the acrylic resin for the clearcoat can be a high molecular weight polyethyl methacrylate resin such asElvacite 2042. The acrylic component of the clear coat also can comprisea mixture of Elvacite 2010 and a medium-to-high molecular weightpolymethyl methacrylate resin such as Elvacite 2021. In a furtherembodiment, the acrylic resin component can comprise Elvacite 2042 and alow molecular weight polyethyl methacrylate resin such as Elvacite 2043.Other similar combinations of acrylic resins, their homopolymers andcopolymers, may be used as a component of the clear coat. Generally, theacrylic resin component has a relatively high weight average molecularweight of about 50,000 to about 400,000.

The PVDF and acrylic-based clear coat formulation can be prepared as asolution of PVDF in the acrylic resin and solvent. Experimental tests offinished car body panels, in which the paint coat has been prepared froma solution of PVDF in acrylic resin, have demonstrated high levels ofgloss and distinctiveness-of-image. The experimental text results aredescribed in Example 11 below.

The PVDF and acrylic-based clear coat formulation also can be preparedas a dispersion of the PVDF in a solution of the acrylic resin. In oneembodiment, the clear coat formulation can be prepared by mixing theacrylic resin with a suitable organic solvent and applying heat todissolve the resin. The mixture is then allowed to cool sufficientlybefore adding the PVDF component so that the PVDF will not dissolve, butwill be maintained as a dispersion in the acrylic-solvent based mixture.By maintaining the PVDF component as a dispersion in the clear coat,solvent evaporation during drying of the clear coat can be improved.

A preferred composition of the dried clear coat comprises from about 50%to about 70% PVDF, and from about 30% to about 50% acrylic resin, byweight. In some instances the maximum content of the PVDF component isabout 65%, with the balance essentially comprising the acrylic resin.These solids ranges are based on the relative proportions of the PVDFand acrylic components only in the clear coat formulation. Other minoramounts of solids, such as UV stabilizers, block copolymers andcompatibilizers also may be contained in the clear coat formulation.

In one embodiment, a successful experimental car body panel havingexterior automotive surface properties was produced from a paint systemin which the dried clear coat consisted essentially of about 50% PVDFand about 50% polymethyl methacrylate resin, by weight. This clear coatprovided high gloss (after thermoforming) and good exterior automotiveproperties of appearance and durability. In another successfulexperimental car body panel having good exterior automotive appearanceand durability properties, including gloss, the dried clear coatconsisted essentially of about 65% PVDF and about 35% polyethylmethacrylate resin, by weight.

The acrylic resin component of the clear coat is desirable because ofits compatibility with the PVDF in dry film form. The acrylic componentis added to the PVDF in an amount that prevents deglossing of thefinished clear coat during thermoforming. The acrylic resin is alsoadded in an amount that yields a transparent clear coat in dry filmform. Generally speaking, transparency and distinctiveness-of-image ofthe composite paint coat increase in proportion to the amount of acrylicresin added to the PVDF-acrylic system. It has been determined that apure PVDF clear coat has reasonably good properties of durability andelongation, but such a 100% PVDF coating is not normally transparent andit deglosses excessively when heated to normal thermoformingtemperatures. When sufficient acrylic resin is added to the PVDFcomponent, the resulting clear coat becomes reasonably transparent andcan resist deglossing at thermoforming temperatures. Increasedtransparency of the clear coat improves the gloss level of the finishedclear coat. The acrylic resin is also combined with the PVDF in anamount that maintains sufficient elongation to allow the clear coat (andthe color coat to which it is bonded) to be thermoformed (as part of thelaminate described below) into complex three-dimensional shapes, whileretaining the exterior automotive durability properties and appearanceproperties, including gloss, of the finished paint coat. It has beendetermined that a dry film-form PVDF-acrylic-based clear coat containingmore than about 35% acrylic resin and less than about 65% to 70% PVDF,by weight of the total PVDF and acrylic solids, avoids deglossing duringthermoforming while achieving sufficient elongation.

It is believed that deglossing of a PVDF and acrylic resin-based clearcoat, in some instances, can be caused by crystallization of the clearcoat as it cools down after thermoforming. Greater crystallization ofthe PVDF-acrylic-based clear coat also is believed to be caused, atleast in part, by proportionately higher thermoforming temperatures.Addition of the acrylic resin to the PVDF in the clear coat formulationmay prevent crystallization of the PVDF in cool-down from thermoformingat normal thermoforming temperatures. Use of polymethyl methacrylate asthe predominant component of the clear coat acrylic resin may bedesirable because it produces a higher gloss level than polyethylmethacrylate. It is believed that the higher gloss results from a slowerrate of crystallization of the polymethyl methacrylate during cooling.It is also believed that deglossing, in certain instances, may be causedby microcracking of the clear coat surface during thermoforming. Use ofa certain amount of softer acrylic resin than polymethyl methacrylate,such as polyethyl methacrylate, may in some instances produce a highgloss surface of the clear coat after thermoforming, particularly incombination with lower thermoforming temperatures.

To the extent that deglossing of the clear coat may be caused bynon-uniform coalescence of the PVDF component in the resin system, it isbelieved that this problem can be overcome by a more uniformly blendeddispersion of the PVDF in the acrylic resin or use of a solution-basedsystem.

The PVDF component of the clear coat is desirable because of theexterior automotive durability properties and the elongation propertiesit provides in the resulting clear coat, particularly in combinationwith the acrylic resin component. The PVDF component also provides goodweatherability properties in the finished paint coat. It has beendetermined that a pure thermoplastic acrylic resin clear coat canprovide good hardness or toughness characteristics, but it lacksweatherability. A pure acrylic resin clear coat also createsdifficulties in separating from the injection mold after theinjection-cladding step. A cross-linked thermoset acrylic resin commonlyused as an exterior auto paint is not useful in the process of thisinvention. When thermoformed, it shatters or cracks when a vacuum isdrawn on the laminate to which it is coated. A dry film-form PVDF andacrylic resin-containing clear coat having from about 30% to about 50%acrylic resin (by weight of the total PVDF-acrylic-based solids) hassufficient elongation to allow proper thermoforming andinjection-cladding, while maintaining the exterior automotivedurability, gloss and other appearance properties of the finishedcomposite paint coat.

The color coat 46 is bonded to the clear coat after the clear coat hasbeen dried on the carrier sheet. The color coat can be coated onto thedried clear coat, or the color coat can be coated onto a separatepolyester casting film, dried, and later transferred from the castingfilm to the clear coat. In either case, the color coat is preferablyapplied to the casting film by reverse roller coating techniques similarto those illustrated in FIG. 5. A preferred dry film thickness of thecolor coat is in the range of about 0.5 to about 1.5 mils. The colorcoat comprises a thermoplastic synthetic resinous coating compositioncontaining a sufficient amount of pigment to provide the appearancenecessary for exterior automotive use in the finished article. Morespecifically, the color coat contains a sufficient amount of pigment sothat the composite paint coat maintains sufficient opacity anddistinctiveness-of-image and avoids stress whitening throughout thethermoforming step so to function as an exterior automotive paint coat.The resinous material contained in the color coat functions incombination with the clear coat to produce the required exteriorautomotive surface for the finished paint coat. That is, although theclear coat provides the exterior surface portion of the finished paintcoat, the exterior automotive properties of the finished surface are notcontrolled solely by the clear coat formulation. The underlying colorcoat can affect durability properties of the finished paint coat, forexample. Abrasion resistance is an example of a mechanical propertyenhanced by a tougher color coat in combination with the exterior clearcoat. Weatherability of the finished paint coat also is influenced bythe color coat formulation as well as the clear coat. The color coatalso comprises a resinous material which is capable of sufficientelongation at thermoforming temperatures so as to not disrupt theexterior automotive properties of the finished paint coat.

The color coat is preferably dried by passing it through the samemultiple heating zones used in drying the clear coat. Dryingtemperatures in each of the zones are progressively increased and can beat about the same temperatures as those used for drying the clear coat.Preferably, similar resinous components with mutually compatiblesolvents are used in the clear coat and color coat so that adhesionbetween the clear coat and color coat is produced without requiringadditional stabilizers or additives. The color coat composition ispreferably a synthetic resinous coating composition having thermoplasticproperties similar to the clear coat. Although the color coat alone doesnot necessarily require all of the exterior automotive properties ofdurability and appearance, in order to produce a useful composite paintcoat, a color coat composition (exclusive of the pigment contained inthe coating) having most of the desirable exterior automotive durabilityproperties is preferred. In one embodiment, the color coat comprises ablended thermoplastic fluorinated polymer and acrylic resin-containingpaint system. This paint system can be similar to the PVDF andacrylic-based coating used in the clear coat. The fluorinated polymercomponent also can include copolymers and terpolymers of vinylidenefluoride. The color coat formulation can be prepared by mixing theacrylic component with suitable organic solvents and applying heat toallow the acrylic resin to dissolve. In a preferred embodiment the PVDFcomponent is dissolved in the acrylic resin solution, although the PVDFcan be maintained as a dispersion in the acrylic-based system. Thepigment is then added to the PVDF-acrylic composition. Preferably, thecomposition of the dried color coat (the PVDF and acrylic-based solids,exclusive the pigment) comprises from about 50% to about 70% PVDF andfrom about 30% to about 50% acrylic resin, by weight of the total PVDFand acrylic solids. In a preferred dispersion formulation, the driedcolor coat comprises about 65% PVDF and about 35% acrylic resin, byweight. The preferred acrylic component for the color coat is apolyethyl methacrylate resin such as Elvacite 2042 or Elvacite 2043, ormixtures thereof. The relatively higher amount of PVDF in the color coatproduces a softer film and therefore enhances elongation properties.

The color coat may contain a substantial pigment level in order toprovide sufficient opacity to maintain desirable coloration in thefinished article. In a highly contoured three-dimensionally shapedarticle, a large amount of pigment may be necessary for hiding,following subsequent thermoforming steps. For most colors, a pigmentlevel from about 3% to about 30%, by weight of the solids contained inthe coating, also referred to as the pigment-to-binder ratio, producesthe desired opacity in the finished paint coat. The amount of pigmentused varies depending upon the color. For a red color coat used in anexperimental car body panel, for example, a pigment level of about 23%,by weight of the total solids, was used. For a black color coat usingcarbon black pigment in an experimental car body panel, about 3% to 5%pigment was used.

The pigment contained in the color coat can affect exterior automotiveproperties. For instance, if the color coat is applied to a laminate asa single paint coat, or is applied to the laminate as an exterior paintcoat, the pigment contained in the coating can cause the color coat todegloss during thermoforming of the laminate. (Under thesecircumstances, the same coating applied as a clear coat may not deglossduring the same thermoforming step.) It has been discovered that afinished paint coat with a high gloss level can be produced with anon-deglossing exterior clear coat applied over a color coat whichotherwise deglosses by itself during thermoforming. Stated another way,a color coat which normally deglosses as an exterior coat may be used asan underlying color coat for an exterior clear coat, if the clear coatcan, following thermoforming, produce the gloss necessary for exteriorautomotive use.

As to the deglossing phenomenon, it has been discovered that anotherwise high gloss exterior surface of a color coat, applied to alaminate in a flat (planar) coating of uniform thickness usuallydeglosses when the laminate is thermoformed into a complexthree-dimensional shape. It is believed that such deglossing is causedby the particles added to the coating as pigment penetrating theexterior surface of the coating during the softening and elongation thatoccur during thermoforming. It has also been discovered that suchdeglossing can be overcome by coating (or laminating) the exterior clearcoat over the color coat at sufficient film thickness that the clearcoat can act as a barrier to prevent the color coat pigment particlesfrom migrating from the color coat through the clear coat andpenetrating the surface of the clear coat during the thermoforming step.

The high pigment level in the color coat also can affect mechanicalproperties of the coating, such as durability and elongation. Generally,the high level of pigment contained in the color coat reduces elongationof the coating. The pigment also can reduce the strength or hardness ofthe coating. A color coat which may, by itself, not have all of thedurability properties of an exterior automotive paint coat, can still beuseful in the finished article. However, elongation properties arecritical because the color coat should not inhibit elongation of theclear coat during thermoforming. If the amount of PVDF component in thecolor coat is at least about the same or greater than the amount of theacrylic component in the color coat, elongation properties of the colorcoat are enhanced. In addition, the acrylic component of the color coatformulation can be a high molecular weight, high-strength resin to addback to the color coat the hardness or strength characteristics lost bythe addition of the pigment to the color coat. The greater amount ofPVDF in the color coat also can improve weatherability of the finishedpaint coat.

Thus, the desired color coat formulation provides the appearance anddurability properties which, in combination with the clear coat, producea composite paint coat having the properties suitable for exteriorautomotive use. The color coat also retains sufficient elongation to bethermoformed in combination with the clear coat so that the durabilityand appearance properties, including gloss, of the finished paint coatare not degraded during thermoforming. In one embodiment, anexperimental car body panel was made from a color coat having PVDF inthe range of about 50% to about 70%, and a high molecular weightpolyethyl methacrylate resin in the range of about 30% to about 50%, byweight of the total (non-pigment) solids. This combination produceddurability and appearance properties, including gloss, in the finishedpaint coat sufficient for exterior automotive use.

As an alternative to the PVDF and acrylic resin combination, the colorcoat also can contain other formulations. It is believed that a flexiblepure acrylic resin with the required elongation properties, or certainsofter acrylic copolymers or acrylic dispersion lacquers havingsufficient elongation and durability properties (especiallyweatherability) also can be useful as a color coat formulation. It isalso believed that certain urethanes and vinyl compositions such aspolyvinyl chloride can provide binders for acceptable color coats. Useof a separate color coat not containing a fluorinated polymer such asPVDF can reduce the cost of the finished paint coat.

Although the paint coat has been described in relation to a clear coatand a separate color coat, the paint coat of this invention also may beproduced as a single pigmented thermoplastic synthetic resinous coating,with the pigment highly dispersed in the coating so that deglossing uponthermoforming is resisted. Alternatively, a clear coat having therequired durability and appearance properties may be used in combinationwith an underlying coating or other substrate material which providesthe coloration and other properties necessary for the combination toproduce a finished paint coat suitable for exterior automotive use.

The size coat 47 is next coated onto the dried color coat, either whenthe color coat is coated on clear coat, or when the color coat only iscoated on a separate casting sheet. The size coat bonds the paint coatto the backing sheet used in the laminating step described below. Thesize coat comprises any synthetic resinous material which isheat-activated from the subsequent laminating step to bond the paintcoat to the backing sheet. The preferred dry film thickness of the sizecoat is from about 0.1 to about 1.0 mil. The size coat is preferablyapplied as a thermoplastic and dried in the same multi-stage drying stepused in drying the clear coat and the color coat. The size coat is driedat a temperature which evaporates the solvent without cross-linking theresin. The size coat composition can vary depending upon the compositionof the color coat and the backing sheet to which the paint coat isbonded. For a PVDF-acrylic-based paint coat, an acrylic resin-based sizecoat is preferred for suitable bonding of the paint coat to the backingsheet. In one embodiment, in which the paint coat is adhered to abacking sheet made of acrylonitrile-butydiene-styrene (ABS), the sizecoat comprises a polymethyl methacrylate resin such as Acryloid A-101 (atrademark of Rohm and Haas Co.) dissolved in a suitable solvent. Inanother embodiment in which the backing sheet is a thermoplasticpolyolefin, the size coat preferably comprises a chlorinated polyolefin.

Transfer to Thermoformable Backing Sheet

The paint-coated carrier illustrated in FIG. 4 is next laminated to athermoformable backing sheet by dry paint transfer-laminatingtechniques. The laminating step is illustrated in FIG. 6. FIG. 7schematically illustrates a thermoformable laminate 70 formed after thedry paint transfer-laminating step. The laminate 70 includes thecomposite paint layer 44 (clear coat and color coat) adhered to abacking sheet 72 by the size coat 47. The backing sheet is preferably asemirigid, self-supporting, thin, flat sheet of a synthetic resinousmaterial. The backing sheet is made from a material which is compatiblewith an injection-molded plastic material later used to form thestructural substrate base of the finished article. Preferably, thebacking sheet is made from the same or substantially the same polymericmaterial as the substrate base of the finished article. The backingsheet also is made from a material having a thickness capable ofthermoforming into a complex three-dimensional shape, along with theadhered composite paint coat, without disrupting the exterior automotiveproperties of the paint coat. The material from which the substrate ismolded can contain a substantial amount of filler and therefore canproduce an imperfect surface on an article molded from the substratematerial. The laminate 70 is adhered to the otherwise imperfect surfaceof the molded substrate to improve the surface characteristics of thesubstrate panel and produce an outstandingly smooth controlled exteriorautomotive finish. The multi-layered article in its finished formcomprises a high performance essentially defect-free,three-dimensionally shaped paint coat with exterior automotiveproperties in combination with the backing sheet 72, which provides abuffer layer between the substandard surface of the substrate and thefinished paint coat. The backing sheet material minimizes the surfaceimperfections transmitted to the paint coat. The preferred material fromwhich the backing sheet is made is ABS. A preferred ABS material is BorgWarner's Cycolac L.S. Thermoplastic polyolefins (TPO's) includingpolypropylenes and polyethylenes also may be used, as well as polyestersor an amorphous nylon, such as Bexloy C-712, a trademark of DuPont. Useof TPO backing sheets and substrates in a composite structure isdescribed in greater detail below. The thickness of the backing sheetcan vary, but generally it is necessary for the backing sheet to have asufficient thickness to isolate or absorb imperfections in the surfaceof the underlying substrate while presenting a perfectly smooth uppersurface of the paint coat. The backing sheet is also not so thick thatit would otherwise disrupt the elongation characteristics of thelaminate during the subsequent thermoforming step. A desirable range ofthickness of the backing sheet is believed to be from about 10 to 30-40mils, with 20 mils being a preferred thickness for an ABS sheet, forexample.

The laminating step is best understood by referring to the schematicview of FIG. 6, in which the paint-coated carrier 41 is shown stored ona top unwind roll 74 and a flexible 20 mil thick ABS backing sheet 72 isstored on a bottom unwind roll 76. The paint-coated carrier, in oneembodiment, comprises the clear coat and color coat on a single flexiblecasting sheet. The paint-coated casting sheet 41 is passed around a drum77, and the backing sheet 72 passes around a drum 78. The carrier andbacking sheet then pass between a heated laminating drum 79 and a rubberbackup roll 80. The laminating drum 79 is preferably made of steel andis preferably operated at a temperature of about 400° to 425° F. It ispressed into contact with the overlapping sheets to heat them to atemperature sufficient to activate the adhesive in the size coat andpress the two sheets into contact with each other to bond the paint coatto the backing sheet. The rubber backup roll 80 is pressed into contactwith the laminating roll, preferably at a pressure of about 300 poundsper lineal inch. The slow speed at which the sheets travel duringlaminating ensures that the resulting laminate 70 is heated to atemperature approaching the temperature of the laminating drum. Thissoftens the backing sheet material somewhat as well as activating theheat-activated size coat to ensure a complete bond between the paintcoat and the backing sheet. The polyester carrier sheet of thepaint-coated carrier has a heat-resistance well above laminatingtemperatures so the carrier sheet resists elongation during thelaminating step. Following the bonding step, the flexible paint-coatedlaminate 70 is then passed around one or more chill rollers 82 forcooling the laminate to room temperature. The laminate 70 then passesonto a laminate rewind drum 84. The carrier sheet is stripped away fromthe laminate prior to the subsequent thermoforming step. This leaves asmooth, defect-free high gloss exterior surface on the clear coat whichreplicates the high gloss surface present on the carrier sheet.

The thermoformable laminate 70 illustrated in FIG. 7 also can be formedby separate laminating steps, each similar to the laminating stepillustrated in FIG. 6. In this embodiment, a separate color coat isfirst transferred from a casting sheet to the backing sheet. The colorcoat may have a size coat to bond the color coat to the backing sheet.The casting sheet is stripped away after laminating. The dried clearcoat is then transferred from a separate casting sheet to the face ofthe color coat opposite from the backing sheet. No size coat isnecessary to bond the clear coat to the color coat during the hotlaminating step.

Thermoforming

In the next step in the process, the laminate 70 shown in FIG. 7 isthermoformed into a desired three-dimensional shape. FIGS. 8 and 9illustrate one example of a thermoforming step in which the initiallyflat laminate can be formed into a highly contoured three-dimensionalshape for use as the surface of a car body panel. Referring to FIGS. 8and 9, separate laminate sheets are individually placed inside aclamping frame 106 of a vacuum-forming machine. The clamping frame ismovable back and forth on a track 108. The laminate sheet is initiallyplaced in the clamping frame at the position shown in phantom lines at106 in FIG. 8.

The clamping frame is then moved along the track into an oven 110 forheating the back sheet to a thermoforming temperature. An ABS backingsheet is heated to a temperature in the range of about 280° to about380° F., and for Bexloy nylon the sheet is heated to a temperature fromabout 380° to about 420° F. These temperatures are actual sheettemperatures, not oven temperatures. The actual thermoformingtemperatures used, within these ranges, may be a factor in preventingdeglossing of the clear coat during thermoforming. In some instancesdescribed in the examples below, a lower thermoforming temperature canprevent deglossing or formation of small cracks in the surface of thepaint coat. These phenomena may otherwise occur at higher thermoformingtemperatures. A pressure assist can be used with the thermoforming stepin order to reduce the thermoforming temperature. A lower thermoformingtemperature of about 270° F. may assist in producing higher gloss anddistinctiveness-of-image in the finished surface. At thermoformingtemperatures the laminate 70 sags as shown at phantom lines at the rightside of FIG. 8.

After the laminate is heated in the oven 110 to the desired temperature,the clamping frame is moved back along the track, away from the oven 110to its original position above a vacuum-forming buck 112. The workingsurface of the vacuum-forming buck 112 is shown in FIGS. 8 and 9 as acurved surface, by way of example only. Other configurations can be useddepending upon the desired three-dimensional shape imparted to thesurface of the finished article.

The preheated laminate is next vacuum-formed into the desiredthree-dimensional shape by first drawing a vacuum on the vacuum-formingbuck 112 through its connection 114 to a vacuum pump. The vacuum-formingbuck 112 is then raised to the position shown in FIG. 9, where it hasrisen into the clamping frame. The vacuum is pulled through holes in thebuck to force the molten plastic into the shape of the working surfaceof the buck. Positive air pressure can be applied to the free face ofthe clear coat on the opposite side of the back to increase formingpressure. The buck stays in place long enough to cool the plastic to asolid state again before the buck drops away back to the position shownin FIG. 8. This leaves behind the plastic in the shape of the buck. Thepreferred vacuum-forming step is to use a male vacuum former in whichthe vacuum-forming buck 112 is in direct contact with the backing sheetso as to not contact the exterior clear coat 45 on the opposite side ofthe backing sheet. In this way, the backing sheet hides most of any ofthe possible defects in the working surface of the buck; and the surfaceof the clear coat is not affected, but is allowed to elongate freely.

In an alternate thermoforming step (not shown), the laminate 70 can befed to the thermoformer as a continuous sheet. The laminate first passesthrough the oven and then passes to the thermoforming buck in line withthe downstream end of the oven. The continuous sheet is stopped atpreset intervals for heating the laminate to the thermoformingtemperature while a previously heated portion of the sheet is vacuumformed into the desired shape.

The thermoforming step produces a three-dimensionally shaped preformedlaminate 116 illustrated in FIGS. 10 and 11. For simplicity, thepreformed laminate is illustrated as comprising the backing sheet 72 andthe composite paint coat 44 adhered to it. The laminate is illustratedin a three-dimensionally shaped form following the thermoforming step asone example only of a possible three-dimensional shape. Other complexthree-dimensional shapes are also possible. The composite paint coatresists elongation greater than about 40% during thermoforming withoutdeglossing, cracking, stress-whitening, or otherwise appreciablydisrupting the exterior automotive durability and appearance propertiesthat were present in the composite paint coat before thermoforming.

Bonding of Thermoformed Laminate to Substrate Panel

FIGS. 10 and 11 schematically illustrate steps in a subsequentinjection-cladding operation in which the preformed laminate 116 isadhered to an underlying plastic substrate panel. The injection-claddingstep is an example of a possible means for adhering the laminate to thesubstrate. Following the thermoforming step, the laminate is placed inan injection mold 117 and fused to the face of an injection-moldedsubstrate 118. FIG. 10 illustrates a first step in theinjection-cladding step in which a plastic injection mold is in its openposition, and the preformed laminate 116 is placed in the mold cavitybetween front and rear mold halves 120 and 122. The inside surface 124of the mold half 120 identically matches the exterior contour of thepaint-coated surface of the preformed laminate. This surface 124 of themold is a rigid, high gloss, highly-polished surface which is free ofsurface defects so that surface defects are not transferred to the highgloss, clear-coated surface of the laminate. After the laminate ispreformed to its desired shape, it is trimmed to size and is ready forinjection-cladding. The vacuum-formed die cut sheet is placed inside theinjection mold and the mold halves 120 and 122 are closed, leaving aspace of the desired size behind the laminate for receiving theinjection molding material. As shown best in FIG. 11, the injectionmolding material 118 flows through a passage 126 in the rear mold half122 and into the mold cavity behind the preformed laminate 116. Themolding material conforms to the shape of the mold cavity and ispermanently fused to the backing sheet portion of the laminate. Theinjection molding material does not come into contact with the paintcoat. As described previously, the molding materials from which thesubstrate 118 and the backing sheet 72 are made are compatible so thatthe two materials fuse to form an integral molded substrate on which thepaint coat provides a defect-free finish. The temperature at which theinjection-mold is operated is substantially below the melt temperatureof the molding material. In one embodiment, in which an ABS backingsheet is used, the molten material is at a temperature of about 450° F.,for example. A water jacket can be used to cool the faces of the mold.During injection-molding, the backing sheet material softens when fusingto the injection molding material, and the surface of the clear coatreplicates the surface of the mold, owing to the pressure from themolding operation. Both faces of the mold are cooled to a temperature inthe range of about 160° to 170° F., so that the paint coat 44 on thelaminate remains stable during injection molding. The clear coatmaterial at the time of injection molding has had all of its solvent gasremoved so that evolution of gases during injection molding isessentially avoided. As a result, the clear coat retains its high glosssurface characteristics during the injection molding step.

FIG. 12 schematically illustrates the finished article 130 produced bythe process of this invention. In the finished article, the preformedlaminate and its backing sheet have been fused to the molded substrate118. In one embodiment, the article can be an exterior car body memberor panel. The exterior clear coat 45 and the color coat 46 combine toproduce a paint coat with exterior automotive properties on the surfaceof the substrate. Any defects in the substrate material have beenabsorbed by the 20 mil thick backing sheet 72 to provide a defect-freepaint coat.

Alternatively, the color coat may in some instances be eliminated or thepigmentation reduced, and the coloration may be provided by pigmentscontained in the backing sheet or molding material for the substrate. Inthese instances, the clear coat is used with the backing sheet which isthermoformed and then adhered to the substrate according to theprocessing techniques described previously. As one advantage, colorationcontained in the backing sheet can hide the effects of chipping of thepaint coat.

Although the invention has been described with respect to theinjection-molding steps illustrated in FIGS. 10 and 11, other techniquescan be used for forming the finished article illustrated in FIG. 12.These include, but are not limited to, use of sheet molding compound(SMC), compression cladding and reaction injection molding (RIM)techniques, and pressure-sensitive or adhesive bonding techniques. Otherplastic molding materials also can be used in place of ABS for fusingthe substrate panel to the paint-coated backing sheet. These may includethermoplastic polyolefins (TPO's) such as polypropylenes andpolyethylenes; polyesters; and amorphous nylon. In these instances, thebacking sheet is preferably made from the same polymeric material as theinjection molding material.

Characteristics of Finished Paint Coat

The following is a list of physical properties which are used herein tomeasure whether the finished paint coat is useful as an exteriorautomotive paint coat:

(1) Gloss

(2) Distinctiveness-of-Image

(3) Color Uniformity (hiding ability)

(4) Dry Film Thickness Uniformity

(5) Gasoline Resistance

(6) Solvent Resistance

(7) Acid Spotting Resistance

(8) Hardness

(9) Abrasion Resistance

(10) Impact Strength

(11) Adhesion of Paint Coat

(12) Accelerated UV Resistance

(13) Resistance to Water and Humidity Exposure

Properties (1) through (4) are considered appearance properties andproperties (5) through (13) are considered durability properties.Specifications and test methods for each of these physical propertiesare described below. Certain specifications and test methods identifiedbelow are defined by publicly available standard industry specificationsand test methods which are incorporated herein by this reference.

(1) Gloss is measured by specular reflectance of a beam of light atangles of 20° and 60°. The desired specular reflectance for an exteriorautomotive paint coat surface is at least about 60 to 65 gloss units at20°, and at least about 75 to 80 gloss units at 60°. Specularreflectance and other criteria herein are measured before the finishedpainted surface is buffed and waxed. A preferred test method isdescribed in GM Test Specification TM-204-A. The Byk-Mallinckrodt"multigloss" or "single gloss" gloss meters can be used for measuringspecular gloss of the finished surface. These gloss meters give valuesequivalent to those obtained from ASTM Method D-523-67. Either glossmeter is used with gloss standards covering the expected range ofmeasurement, together with a piece of polished black glass plate ofknown refractive index. The gloss meter is calibrated by setting it toread the gloss of a highly polished standard and then reading the glossof a working standard having a value preferably in the range of the testpanel. The second standard should agree within one unit of its assignedvalue. At least two readings are taken on a different area of the testpanel. These values are averaged if they agree within one unit. If therange is larger than one unit, additional regions are taken and a meanvalue is calculated.

(2) Distinctiveness-of-Image (DOI) is a measurement of the clarity of animage reflected by the finished surface. DOI can be measured from theangle of reflection of a light beam from a spherical surface. Thedesired DOI for an exterior automotive paint coat surface is at leastabout 60 units, where 100 units is the maximum DOI reading. DOI ismeasured by the Hunterlab Model No. D47R-6F Dorigon Gloss Meter. A testpanel is placed on the instrument sensor and the sharpness of thereflected image is measured. Details of the DOI test procedure aredescribed in GM Test Specification TM-204-M, which are incorporatedherein by reference.

(3) Color Uniformity is a test to determine whether coloration of thepaint coat remains uniform after thermoforming and injection-cladding.Coloration is tested after the paint coat is coated on the castingsheet, before transfer to the backing sheet. Coloration testing isrepeated after a deep draw stretch simulating elongation duringthermoforming, to determine whether the color has changed. A desirablecoloration uniformity can be a color change of no greater than about oneto two McAdam units on a colorimeter.

(4) Dry Film Thickness (DFT) is a standard industry measurement of thefilm thickness of the finished paint coat, to determine whether thepaint coat thickness matches a required film thickness specified by theauto manufacturer. For the present exterior automotive specifications,uniformity of the finished paint coat is determined to be a more usefulparameter in determining whether the paint coat meets appearancerequirements. Thickness uniformity of the finished paint coat can bemeasured from several locations on the finished article, includinghighly contoured areas, to determine whether variations in the thicknessof the finished paint coat exceed a desired level.

(5) Gasoline Resistance requires no color change, degradation,tackiness, marring or loss of paint adhesion on plastic parts used onand adjacent to fuel filler openings after being immersed for tenseconds, ten times, in a specified reference fuel with a 20 second dryoff period between each immersion. Immediately after the tenthimmersion, the painted surface is checked and must pass ThumbnailHardness according to GM Test Specification TM 55-6, incorporated hereinby reference..

(6) Cleanability is tested according to GM Test Specification TM 31-11which is incorporated herein by reference. According to this test, thepainted plastic part is required to withstand ten rubs with cheeseclothsaturated with 9981062 Naphtha or currently used and approved cleaningsolvents, with no evidence of staining, discoloration, or softening ofthe painted surface. This test requires no evidence of color transferfrom the test part to the cloth. One rub consists of one forward andbackward motion.

(7) Acid Spotting Resistance requires the test part to withstandexposure to 0.1N sulfuric acid for 16 hours without any evidence ofstaining, discoloration, or softening of the painted surface.

(8) Hardness is measured by a standard Knoop Hardness Test. The requiredhardness is at least a Knoop hardness number of four.

(9) Abrasion Resistance is tested by a gravelometer under the standardtest method identified as SAE J-400. According to this test, the paintedpart shall withstand the Gravelometer Test at minus 10° F. with aminimum rating of eight (F.B. Gravelometer Rating Chart). The testedpart should withstand the Gravelometer Test as-received and afterFlorida exposure described below. A Fisher Body Material SpecificationFBMS 26-7 (incorporated herein by reference) also defines a minimumlevel of wear resistance for the finished paint coat.

(10) Impact Strength is tested at room temperature by the Gardener Testand by the Rosand Test at minus 20° F. The paint coat should withstandat least 20 inch-pounds of direct impact with no failure.

(11) Paint Adhesion is tested by a standard Tape Adhesion Test describedin GM Test Specification TM 55-3, which is incorporated herein byreference. According to this test, a tape is pressed down over anX-shaped cut in the paint coat and the tape is then removed to test theamount of peeling. The Adhesion Test requires a minimum of 99% of thepaint remaining in the tape test area.

(12) Accelerated UV Resistance, also referred to as AcceleratedWeathering, or QUV, measures the weatherability of a paint coat inaccelerated test procedures designed to provide an accurate indicationof long-term UV resistance or other weatherability properties. Accordingto a QUV test useful for measuring accelerated UV Resistance, the testpanel should not show any significant surface deterioration orembrittlement, loss of coating adhesion, objectionable shrinkage, ornoticeable color or gloss change after about 500 to 1,000 hours exposureto UV light and condensation apparatus per ASTM G-53 using eight hour UVcycle at 70° C. and four hour humidity cycle at 50° C.

(13) Resistance to Water and Humidity Exposure is measured by severaltests. According to a first test, the finished part shall withstand 96hours of humidity exposure at 100% relative humidity and 100° F. in ahumidity cabinet defined in GM test specification TM 55-3, and atwo-hour water immersion test at 100° F. according to GM testspecification TM 55-12. These test specifications are incorporatedherein by reference. The resulting test panel should show no evidence ofblistering when examined one minute after removal from the test cabinetand shall withstand the Paint Adhesion Test described above. The PaintAdhesion Test is performed within one minute after removal from eithertest cabinet. In a second test, the finished part should withstand 15cycles of the Moisture-Cold Cycle Test defined in GM test specificationTM 45-61A (incorporated herein by reference), without any visible signsof cracking or blistering. After 15 cycles, the part shall withstand 96hours of the humidity exposure described above, followed by passing thePaint Adhesion Test also described above. The Paint Adhesion Test isperformed within one minute after removal from the humidity environment.One cycle consists of 24 hours and 100% relative humidity at 100° F., 20hours at minus 10° F., and four hours at room temperature.

Other durability tests can be used to determine the usefulness of apaint coat for exterior automotive applications. These tests can includelong-term ultraviolet radiation exposure and heat exposure tests. Bothof these tests require long-term exposure of the panel to the particularenvironment. For instance, one long-term UV test can require two yearsexposure to determine the long-term resistance of the paint coat toultraviolet radiation. In a long-term weathering and heat resistancetest, the painted plastic part is required to withstand two years directFlorida and Arizona test site exposure without any significant color orgloss change, loss of adhesion, or other detrimental surface orsubstrate deterioration effects. After long-term Florida and/or Arizonaexposure, painted samples must withstand testing under the TapeAdhesion, Abrasion, Gravelometer and Moisture-Cold Crack Cycling tests.Five years Florida and Arizona test site exposure also can be used.Other test methods can include sulfide staining, detergent resistance,solvent resistance, compatibility, cycle tests, humidity and adhesion,humidity and wear resistance, cold exposure, and Florida and Arizonaexposure tests set forth in FBMS 26-7.

EXAMPLE 1

A high gloss jet black laminated exterior automotive paint coat wasformed on the exterior surface of an experimental plastic rear windowmolding for a Pontiac Grand AM. The window molding was similar to thatshown in FIG. 2. The paint coat was first coated onto a surface of aflexible polyester film casting sheet. The flexible carrier comprisedtwo mil thick high gloss American Hoechst 3000 polyester film. The paintcoat comprised a clear coat, a color coat, and a size coat coated ontothe polyester film casting sheet in that order. A thin film of wax wasfirst coated on the polyester film. The wax coating formulationcomprised, on a weight basis, 40% xylene, 59.4% cyclohexanone, and 0.6%carnauba wax. The wax was dissolved in the solvents at 120° F. and caston the polyester film using a gravure coating cylinder. The wax coatingwas applied as a thin film approximately 0.001 mil thick. The wax-coatedcasting sheet was then passed through a drying oven and dried at 250° F.with a line speed of 25 feet per minute. The wax-coated casting sheetcould be separately run at a higher lineal speed, if desired. The waxfilm did not affect replication of the polyester film surface by theclear coat.

The clear coat was then prepared from the following formulation:

    ______________________________________                                        Ingredient         Parts                                                      ______________________________________                                        BLO (Butyrolactone)                                                                              15.00                                                      DIBK (di-isobutyl ketone)                                                                        27.00                                                      Polymethyl methacrylate                                                                          18.00                                                      (Elvacite 2010)                                                               PVDF (Kynar 301F)  18.00                                                      BLO                6.28                                                       Cyclohexanone      15.00                                                      Silicone fluid     0.72                                                       (Dow Corning DC-11)                                                           ______________________________________                                    

The Elvacite 2010 acrylic resin was mixed with the BLO and DIBK solventsunder heat applied at approximately 130° F. to dissolve the acrylicresin in the solvents. The resulting mixture was then allowed to coolover night. The PVDF, together with the remainder of the BLO andcyclohexanone solvents and the silicone fluid, were then mixed at roomtemperatures so that the PVDF component remained as a dispersion in themixture, rather than dissolving. The dried clear coat containedapproximately 50% PVDF and 50% polymethyl methacrylate, by weight, basedon the total PVDF-acrylic solids.

The clear coat was coated on the casting sheet in a dry film thicknessof about 0.8 mil. The clear coat was applied to the sheet by a reverseroll coater (illustrated in FIG. 5) in line with the gravure ovenpreviously used for drying the wax film, so that the clear coat wasapplied directly after drying of the wax. The clear coat was dried onthe carrier sheet by passing it through a multi-zone impinging airdrying oven having three heating zones spaced apart axially along thelength of the carrier, with each drying zone having a progressivelyhigher temperature. The clear-coated carrier was passed through theheating zones at a line speed of 25 feet per minute and each heatingzone was 40 feet long. Temperatures of the three heating zones were:Zone 1: 260° F., Zone 2: 330° F., Zone 3: 390° F. Passing the clear coatthrough the three heating zones removed substantially all solvent gasesfrom the clear coat to produce a dry clear coat of uniform filmthickness.

A jet black color coat was next coated on the dried clear coat at a dryfilm thickness of about 0.8 mil. The color coat formulation was asfollows:

    ______________________________________                                        Ingredient        Parts                                                       ______________________________________                                        Cyclohexanone     9.27                                                        DIBK              18.54                                                       BLO               8.34                                                        Polyethyl methacrylate                                                                          10.02                                                       (Elvacite 2042)                                                               Dispersing agent  0.10                                                        (Solsperse 17,000)                                                            PVDF (Kynar 301F) 24.04                                                       BLO               14.14                                                       Black Dispersion  15.00                                                       ______________________________________                                    

The black dispersion comprised carbon black in a vehicle of Elvacite2043, available commercially as Gibraltar 438-39110 pigment. The colorcoat formulation was prepared in a similar manner to the clear coatformulation in that the acrylic resin was first dissolved in thecyclohexanone, DIBK and BLO solvents at a temperature of about 130° F.and was then allowed to cool before the PVDF component was added to themixture to form a dispersion of the PVDF in the acrylic resin. Thepigment was then added to the resulting mixture to produce a jet blackcolor. On a weight basis, the amount of pigment contained in the colorcoat formulation was about 4% to about 5%. The dried color coatcomprised approximately 65% PVDF and approximately 35% acrylic resin, byweight of the total PVDF and acrylic (non-pigment) solids. The acrylicresin component comprised polyethyl methacrylate comprised ofapproximately 90% Elvacite 2042 and approximately 10% Elvacite 2043. Thecolor coat was coated onto the dried clear coat in liquid form and thenpassed through the three stage oven described above to dry the colorcoat.

A size coat was next prepared for use with an ABS backing sheet. Thesize coat comprised 50 parts methyl methacrylate resin known as AcryloidA-101 (a trademark of Rohm and Haas Co.) dissolved in 50 partsmethylethyl-ketone solvent. The size coat was coated onto the driedcolor coat in a dry film thickness of about 0.1 mil using a singlestation gravure coating cylinder. The size coat was then dried bypassing it through a single stage drying oven at a temperature of about275° F.

The resulting paint-coated carrier was then passed to a laminatingoperation similar to that illustrated in FIG. 6, where the paint coatwas transferred from the polyester carrier to a 20 mil thick ABS backingsheet. In the laminating operation, the backing sheet and thepaint-coated carrier were run at a lineal speed of 15 feet per minute,and the laminating drum was operated at a temperature of 400° F. Thesize coat was heat-activated and the paint coat was transferred from thecarrier to the face of the ABS backing sheet during the laminatingoperation, in which the hot steel drum applied a force of about 300pounds per lineal inch. The polyester carrier film was stripped awayfrom the surface of the laminate, leaving the paint coat bonded to theABS sheet, with the clear coat providing a high gloss surface on theexterior of the ABS backing sheet.

The paint-coated laminate was then thermoformed into a complexthree-dimensional shape to form the plastic window molding. The laminatewas thermoformed by first heating the flat laminate in an oven to atemperature of about 360° F., to soften the laminate. After the laminatewas heated, it was placed over a vacuum-former buck similar to thatshown in FIGS. 8 and 9, and a vacuum was drawn against the buck on theABS side of the laminate to form the heated laminate into thethree-dimensional shape of the window molding.

The thermoformed laminate was then trimmed to fit in the mold cavity ofa plastic injection molding machine. An ABS plastic molding material,for forming the substrate base of the window molding, was injected intothe mold behind the thermoformed laminate to fuse the ABS moldingmaterial to the laminate. The mold was operated at normal melttemperature for the ABS resin. This formed a window molding as aintegral plastic part with a defect-free, paint coat on the exteriorsurface of the panel.

The window panel was tested and the tests demonstrated the usefulness ofthe paint coat as an exterior automotive paint coat. The test resultsindicated that desirable appearance properties, including gloss, wereproduced. Gloss measured 62 units at 20° and 79 units at 60°. DOImeasured 64. Color uniformity was good. The test results alsodemonstrated a desirable combination of durability properties. The testpanel passed gasoline resistance, acid resistance, abrasion resistance(gravelometer reading of 8), impact resistance (80 in-lb. for GardnerTest), QUV, and 96-hour humidity exposure tests, according to testmethods similar to those described above.

EXAMPLE 2

A high gloss red laminated exterior automotive paint coat was formed onthe exterior surface of a highly contoured plastic automobile bodypanel. The laminate was matched to a General Motors Fiero red body colorand used to make a prototype injection-clad Fiero rear quarter panel.The paint coat was first coated onto a casting film comprising a two milthick high gloss American Hoechst 3000 polyester film. A clear coat,color coat, and size coat were coated onto the casting film in thatorder. The clear coat was prepared from the following formulation:

    ______________________________________                                        Ingredient         Parts                                                      ______________________________________                                        Cyclohexanone      15.47                                                      BW (Butyrolactone) 7.52                                                       DIBK (di-isobutyl ketone)                                                                        21.66                                                      Polyethyl methacrylate                                                                           12.95                                                      (Elvacite 2042)                                                               UV absorbers       1.1                                                        PVDF (Kynar 301F)  24.05                                                      BLO                17.24                                                      ______________________________________                                    

The Elvacite acrylic resin was dissolved in the BLO, DIBK andcyclohexanone solvents, while mixing and under heat at approximately130° F. The resulting mixture was allowed to cool overnight. The UVabsorbers were then added to the mixture and the PVDF was dispersed inthe resin. The remaining BLO solvent was added to dilute the finalmixture. The PVDF component remained as a dispersion in the mixturerather than dissolving. The dried clear coat contained approximately 65%PVDF and 35% acrylic resin, based on the total PVDF and acrylic solids.

The clear coat was coated on the casting film in a dry film thickness of0.6 mil. The wax coat described in Example 1 was omitted in this test.The clear coat was dried on the casting sheet by passing it through thesame three-zone drying oven described in Example 1. Line speed andtemperatures of the three zones were the same. Passing the clear coatthrough the drying oven removed substantially all solvent gases from theclear coat and produced a dry clear coat of uniform film thickness.

A red color coat was next coated on the dried clear coat at a filmthickness of about 0.8 mil. The color coat formulation was as follows:

    ______________________________________                                        Ingredient        Parts                                                       ______________________________________                                        Cyclohexanone     10.61                                                       Polyethyl methacrylate                                                                          2.99                                                        (Elvacite 2042)                                                               Dispersing agent  0.10                                                        (Solsperse 17,000)                                                            PVDF (Kynar 301F) 19.95                                                       BLO               4.02                                                        Solvent (M-Pyrol) 8.45                                                        Red Dispersion    57.9                                                        ______________________________________                                    

The dispersion comprised several pigments as a powder mixed in a vehiclecomprising polyethyl methacrylate resin, Elvacite 2043, 16% solids, and84% cyclohexanone solvent. The color coat formulation was prepared in asimilar manner to the clear coat formulation, in that the acrylic resinwas first dissolved in the solvents at a temperature of about 130° F.The dispersing agent and a portion of the red dispersion were added. Themixture was allowed to cool to room temperature and the PVDF componentwas dispersed using a high speed mixer. The remainder of the reddispersion was then added to the resulting mixture to produce a redcolor match. The dried color coat comprised approximately 65% PVDF andapproximately 35% acrylic resin, by weight of the total PVDF and acrylic(non-pigment) solids. The acrylic resin component comprised polyethylmethacrylate, approximately 80% Elvacite 2043 and approximately 20%Elvacite 2042. The pigment was present in a ratio of three parts pigmentto ten parts resin binder, or approximately 23% of the total solids. Thecolor coat was coated onto the dried clear coat in liquid form and thenpassed through the three-stage oven described above for drying the colorcoat.

A size coat was next prepared for use with an ABS backing sheet. Thesize coat comprised 75 parts methyl methacrylate resin, Acryloid A-101,dissolved in 25 parts toluene solvent and mixed until homogeneous. (TheAcryloid A-101 comprised 40% PMMA solids in MEK solvent.) The size coatwas then coated onto the dried color coat in a film thickness of about0.1 mil. The size coat was applied by a reverse roll coater similar tothat described in FIG. 5 and was then dried in the same three-stagedrying oven as the clear coat and the color coat. The resultingpaint-coated carrier was transferred to a laminating operation similarto that illustrated in FIG. 6, where the paint coat was transferred fromthe polyester carrier to a 20 mil thick ABS backing sheet. The carrierfilm was stripped away from the surface of the laminate, leaving the redpaint coat with a high gloss surface on the exterior of the ABS backingsheet.

The laminate was then thermoformed into the complex three-dimensionalshape of the rear quarter panel. The laminate was thermoformed bypassing it, as a continuous sheet, through an oven for heating thelaminate to a temperature of about 290° F. After the continuous sheetwas heated to this temperature, it was then moved over a vacuum-formerand a vacuum was drawn to form the laminate into the three-dimensionalshape of the rear quarter panel. Positive air pressure of 15 psi wasapplied to the clear-coated free face of the sheet and the vacuum wasdrawn on the ABS side of the sheet.

The thermoformed laminate was placed in the mold cavity of a plasticinjection mold, and an ABS-based plastic molding material for formingthe substrate base of the quarter panel was injected into the moldbehind the thermoformed laminate, to fuse the molding material to theABS side of the laminate. This formed the rear quarter panel as anintegral plastic part with a defect-free, glossy paint coat on theexterior surface of the panel.

The panel was tested, and the tests demonstrated the usefulness of thepaint coat as an exterior automotive paint coat. The test resultsindicated that desirable appearance properties, including gloss, wereproduced. Gloss measured 65 units at 20° and 80 units at 60°. DOImeasured 65. Color uniformity was good. The test results alsodemonstrated a desirable combination of durability properties. The testpanel passed gasoline resistance, cleanability, acid resistance,hardness (7-8 reading on Knoop hardness scale), abrasion resistance(gravelometer reading of 8), impact resistance (80 in-lb. for GardnerTest), QUV, and 96-hour humidity exposure tests, according to testmethods similar to those described above. Florida exposure passed afterthree months.

EXAMPLE 3

Tests were conducted to determine the relative proportions of the PVDFand acrylic components of the clear coat and the color coat capable ofproducing a composite paint coat that can be cast as a film, laminatedto a backing sheet, thermoformed, and injection-clad to form a finishedarticle with an exterior automotive paint coat surface. In this example,standard spray type automotive acrylic enamel paints manufactured byDuPont were used as a paint coat in the process of this invention. Thesetypes of paint systems are commonly used at present as exteriorautomotive paint. The paint coats were thermoset and they cross-linkedat low temperatures on the carrier when dried. These paint coats werethen transferred from the carrier to a 20 mil thick ABS backing sheetwhich was then drawn on a vacuum-former. The paint coat was too brittleto elongate properly; it cracked and shattered at stress points in thelaminate when thermoformed.

Similar DuPont urethane-based automotive paints normally used on rubberbumpers also failed in a similar manner when thermoformed. These paintsystems were stable at room temperature but they cracked during hightemperature vacuum-forming.

EXAMPLE 4

In a test similar to that described in Example 3, a non-thermosetacrylic lacquer paint coat was evaluated. The paint coat comprised aDuPont lucite dispersion lacquer thermoplastic acrylic resin paintsystem. The paint coat was coated on a casting sheet, dried, andlaminated to a 20 mil thick ABS backing sheet. This paint system couldbe thermoformed, but it was difficult to process. If used as ahigh-solids (low solvent) paint coat, the lacquer took too long to dry.If stabilizers were added to improve drying, it cracked whenthermoformed. It also tended to adhere to the injection mold.

EXAMPLE 5

Other pure thermoplastic acrylic resin paint systems were tested, suchas a polymethyl methacrylate and solvent-based paint coat with dispersedpigments. Such pure acrylic paint systems were characterized primarilyby their difficulty in processing because of their slow rate of solventevaporation during drying and a tendency to adhere to the surface of theinjection mold. Acrylic paint systems with appreciable amounts ofpigment deglossed during thermoforming. Pure thermoplastic acrylic paintsystems also tended to lack certain mechanical properties that did notmeet exterior automotive criteria, including low abrasion resistance(gravelometer) properties. In addition, these pure acrylic resinformulations did not cast well in film form because of their tendency toadhere too strongly to the casting sheet.

EXAMPLE 6

A pure PVDF (Kynar 301F) paint system was tested in the process of thisinvention. The PVDF paint system had sufficient elongation to thermoformproperly without cracking, but it deglossed excessively duringthermoforming.

EXAMPLE 7

A thermoplastic acrylic-vinyl paint system was tested experimentallyaccording to the process of this invention. The paint system alsoincluded a dispersed black pigment, about 3% by weight of the totalsolids. This paint system had been used successfully previously forinterior automotive trim parts on dashboard panels and the like. Thepaint system could be laminated to an ABS backing sheet, but when it wasthermoformed, it deglossed excessively. This interior paint system didnot produce an exterior automotive paint surface that meets minimalgloss and DOI specifications for exterior automotive use. This paintcoat, when used for automotive interior parts, also is not applied witha film thickness necessary to meet durability specifications for anexterior automotive finish. Using the higher level of pigment requiredfor an exterior automotive paint coat produced extreme deglossing duringthermoforming. Other mechanical properties necessary for exterior usealso were not present.

EXAMPLE 8

A blended thermoplastic PVDF-acrylic paint system was testedexperimentally with the process of this invention. This blended paintsystem comprised a dispersion of 72% PVDF and 28% acrylic resin, byweight of the total PVDF-acrylic solids. This paint system was similarto one used commercially on exterior metal trim parts for automobiles inwhich the metal was spray painted and then cold-formed to produce thedesired trim part. This blended paint system contained a dispersion ofblack pigment comprising about 3% by weight of the total solids. Thispaint system was not suitable for exterior automotive use. The paintsystem could be laminated to an ABS backing sheet, but whenthermoformed, it deglossed excessively. In addition to its low gloss,this paint system also did not possess the exterior DOI requirements foran exterior automotive finish.

EXAMPLE 9

A PVDF and acrylic resin clear coat was tested in combination with apure acrylic-based color coat. Each paint coat was coated on a castingsheet, the coatings were dried and transferred to an ABS backing sheetto form a composite paint coat, and the sheet was thermoformed. In onetest, the acrylic resin component in the color coat comprised an outdoorweatherable acrylate known as Korad D, a product of Polymer ExtrudedProducts of Newark, N.J. Other tests were conducted with pure acryliccolor coat formulations comprising PMMA and PEMA copolymers. In onetest, the color coat comprised a pure Elvacite 2042 polyethylmethacrylate. Visual observation of the thermoformed laminates indicatedthat good appearance properties, including gloss and DOI, were achieved.One observation was that a PVDF and acrylic clear coat can be used incombination with a color coat not containing the PVDF component,resulting in a less expensive composite paint coat that eliminates themore expensive fluorocarbon component from a portion of the finishedpaint coat.

EXAMPLE 10

Tests were conducted on a composite paint coat comprising an exteriorclear coat bonded to a color coat. The solids in the clear coat and thecolor coat both consisted essentially of a blended thermoplasticPVDF-acrylic paint system. The paint coat was coated on a casting sheet,transferred to an ABS backing sheet, thermoformed, and injection-clad toan ABS substrate. It was determined that certain PVDF/acrylic ratios inthe clear coat did not produce a sufficient combination of theappearance and durability properties in the finished laminate suitablefor exterior automotive use. For instance, 100% PVDF deglossed duringthermoforming, whereas 100% acrylic resin created processing problems,including adherence to the injection mold and slow solvent evaporation.FIG. 13 shows a graph representing a performance curve for thePVDF-acrylic based composite paint coat. This curve represents therelationship between gloss (gloss units at 60°) of the clear coat on thefinished article and the ratio of PVDF to acrylic in the dried clearcoat, by weight of the total PVDF and acrylic-based solids. This curveis based upon experimental evaluations of clear coat formulationscomprising PVDF and various acrylic resin combinations, primarilycombinations of polymethyl methacrylate and polyethyl methacrylate, ormixtures thereof, including a range of low to very high molecular weightacrylic resins. This curve illustrates that a transition point existsbetween acceptable gloss and unacceptable deglossing above about 65% to70% PVDF in the clear coat formulation. If the PVDF is contained in aformulation greater than about 70%, excessive deglossing is producedupon thermoforming. The tests used to determine the performance curvealso revealed that a 50/50 ratio of PVDF to acrylic is approximatelywhere addition of a greater proportion acrylic resin makes processing ofthe paint system too difficult. The lined portion of the curverepresents a workable combination of PVDF and acrylic resin, for theseparticular resin combinations, to produce a clear coat having adesirable gloss level. The minimum desired gloss level, for the purposeof this example, was selected as 75 units for 60° specular reflectance.These tests have shown that polymethyl methacrylate in the PVDF andacrylic paint system can produce a generally higher gloss level thanpolyethyl methacrylate; and therefore, the curve illustrated in FIG. 13will tend to rise as proportionately more polymethyl methacrylate isused. The curve will become lower as more polyethyl methacrylate isused. Moreover, the tests have shown that addition of pigment to theunderlying color coat may cause greater deglossing of the exterior clearcoat during thermoforming; and therefore, the curve illustrated in FIG.13 will tend to become lowered as the pigment level in the color coatincreases. Tests have also shown that deglossing of the clear coat maybe caused by several factors. For instance, if the clear coat is toothin, the pigment particles from the underlying color coat may migratethrough the surface of the clear coat upon thermoforming and cause atleast some deglossing. In certain instances, a thicker clear coat canresist this type of deglossing. However, in other instances, a thickerclear coat does not prevent deglossing. In one test, a relatively thick(1.2 mil) clear coat comprising 50% PVDF and 50% polymethyl methacrylatedeglossed when thermoformed at 340° F. The underlying color coatcontained a substantial pigment level of 23%. By increasing the PVDF inthe clear coat to 65% solids and by changing the acrylic component to35% polyethyl methacrylate, and by using a lower thermoformingtemperature of 290° F., deglossing of the clear coat was prevented.

EXAMPLE 11

Experiments were conducted to compare the physical properties ofexterior automotive PVDF/acrylic coatings prepared as a solution of PVDFin the acrylic resin with similar dispersion systems. The tests wereconducted for both the clear coat and the color coat to compare glossand distinctiveness-of-image (DOI) levels for thermoformed panels madewith combinations of both solution and dispersion cast PVDF/acrylicfilms. Dispersion and solution clear coats and color coats were producedfrom the following formulations:

    ______________________________________                                        Ingredient         Parts                                                      ______________________________________                                        Dispersion clear coat:                                                        Polymethyl methacrylate                                                                          50                                                         (Elvacite 2010)                                                               PVDF (Kynar 301F)  50                                                         High boiling point acetate                                                                       74                                                         solvent (Exxate 700)                                                          Solvent (M-Pyrol)  55.5                                                       Cyclohexanone      55.5                                                       Solution clear coat:                                                          Polymethyl methacrylate                                                                          50                                                         (Elvacite 2010)                                                               PVDF (Kynar 301F)  50                                                         Solvent (M-Pyrol)  225                                                        Methethylketone    225                                                        Dispersion color coat:                                                        DIBK (di-isobutyi ketone)                                                                        18.55                                                      BLO (Buytrolactone)                                                                              8.34                                                       Polyethyl methacrylate                                                                           10.20                                                      (Elvacite 2042)                                                               Cyclohexanone      9.27                                                       Dispersing agent   0.10                                                       (Solsperse 17,000)                                                            PVDF (Kynar 301F)  24.40                                                      BLO                14.14                                                      Black dispersion   15                                                         Solution color coat:                                                          Polyethyl methacrylate                                                                           10.20                                                      (Elvacite 2042)                                                               Dispersing agent   0.10                                                       (Solsperse 17,000)                                                            PVDF (Kynar 301F)  24.40                                                      Black dispersion   15.00                                                      Solvent (M-Pyrol)  86.00                                                      Methyethylketone   74.30                                                      ______________________________________                                    

The dispersion clear coat was prepared by initially dissolving theElvacite 2010 in the Exxate 700 and the cyclohexanone. The Kynar 301Fwas then dispersed in the resulting mixture using a high speed mixingblade from a Cowles mixer. The M-Pyrol was then added to the resultingmixture. Mixing was at room temperature so that the PVDF componentremained as a dispersion in the mixture rather than dissolving. Thedispersion clear coat was then coated on a casting sheet of polyesterfilm by a reverse roll coater. The clear coat was then dried on thecarrier sheet by the drying techniques described herein.

The solution clear coat was prepared by dissolving both resins in thesolvent blend and by mixing with a high speed Cowles mixer to addsufficient heat to the mixture to completely dissolve the resin. Thesolution clear coat had substantially less solids (less than about 20%PVDF/acrylic solids) than the dispersion clear coat along with use ofstronger solvents to produce a clear solution PVDF/acrylic coating.

The dispersion color coat was prepared by dissolving the Elvacite 2042in the DIBK and Cyclohexanone solvents along with the first part of theBLO solvent. The Kynar 301F was dispersed in the resulting mixture whichwas then diluted with the remaining BLO prior to adding the blackdispersion. The black dispersion comprised carbon black dispersed inElvacite 2042 and cyclohexanone.

The solution color coat was prepared by dissolving both resins in thesolvent and then adding the black dispersion. The color coats were caston separate polyester casting sheets, rather than coating them over adried clear coat. If the base coat is cast over a dried clear coat, thesolvents in the base coat attack the clear coat, especially in asolution-form base coat with its stronger solvents. Both color coatswere then dried on their respective casting sheets.

Four thermoformable laminates were then prepared for testing gloss andDOI. Various combinations of dispersion clear coat, dispersion colorcoat, solution clear coat, and solution color coat PVDF/acryliclaminates, as described below, were prepared. Each thermoformablelaminate comprised a color coat and clear coat laminated to an 18 milABS sheet. The color coat was first laminated to the ABS backing sheet,the polyester casting sheet was stripped away, then the clear coat waslaminated over the color coat and the polyester casting sheet for theclear coat was then stripped away, leaving an ABS thermoformablelaminate with the color coat and exterior clear coat bonded to a face ofthe backing sheet. The backing sheet was then subjected to deep drawthermoforming using a pressure assist (thermoforming temperatures wereapproximately 270°-280° F.) to produce the test panels which were thenmeasured for gloss and DOI levels.

Comparative tests of gloss and DOI for the dispersion and solution paintcoats revealed the following results:

    ______________________________________                                        Laminate    20° gloss                                                                           60° gloss                                                                       DOI                                         ______________________________________                                        Dispersion clear                                                                          66           82       72                                          coat/                                                                         Dispersion color                                                              coat                                                                          Solution clear                                                                            69           82       82                                          coat/                                                                         Dispersion color                                                              coat                                                                          Dispersion clear                                                                          65           81       70                                          coat/                                                                         Solution color                                                                coat                                                                          Solution clear                                                                            70           81       89                                          coat/                                                                         Solution color                                                                coat                                                                          ______________________________________                                    

These test results demonstrated that higher levels of DOI are achievedby using the solution PVDF/acrylic coatings compared with similardispersion coatings. Moreover, the DOI levels are high, greater thanabout 80 units and approaching 90 units in one instance, when thelaminate includes at least a clear coat of solution-form PVDF/acrylicresin. 60° gloss levels remained about the same for solution anddispersion coatings, and these gloss levels were sufficiently high tomeet exterior automotive requirements. 20° gloss levels were somewhathigher with the solution clear coat films. Best results were obtainedwhen the paint coat comprised both a clear coat and an underlying colorcoat of the solution PVDF/acrylic resin.

EXAMPLE 12

The chemical resistance properties of the PVDF/acrylic paint coats ofthis invention were compared with three other commercially usedautomotive paint systems. The results demonstrated that the paint coatof this invention exhibited the best chemical resistance. Two panelscomprising PVDF/methyl methacrylate clear coats according to thisinvention were tested for chemical resistance (acid/alkali spotting).Three additional test panels comprised clear coats and pigmented basecoats made from commercially available thermoplastic lacquer automotivepaint systems which comprised dispersions of polymethyl methacrylatecopolymers. Two additional tests panels comprised a rigid enamel, i.e.,a melamine acrylic thermoset exterior automotive paint, and a flexibleenamel, i.e., a flexible melamine polyester thermoset exteriorautomotive paint. Several test solutions were used, including organicacids, G.M. acid rain, and various concentrations of sulfuric acid,hydrochloric acid and sodium hydroxide. The paint coats of thisinvention achieved the highest rating and were untouched by thedifferent test solutions. Each of the commercial automotive paintsexperienced etching by one or more of the test solutions.

Thermoplastic Polyolefin Backing Sheet and Substrate

Thermoplastic polyolefins (TPO's) such as polypropylene and polyethyleneare useful as a car body substrate material because of their impactresistance, corrosion resistance, and their ability to be formed intodifferent complex configurations. Previously, TPO's have been difficultto paint and this has limited their use in the automotive market.Adhesion of the paint coat to the TPO substrate, particularly, has beena problem. The process of this invention can be used to produce anautomotive quality paint coat on a TPO car body panel, and good adhesioncan be produced between the paint coat and the TPO composite structureforming the underlying car body panel.

Briefly, in this embodiment of the invention, a thin size layer of athermoplastic chlorinated polyolefin (CPO) is coated between the paintcoat layer on the flexible carrier film and the flexible TPO backingsheet. This composite structure is then thermoformed and bonded to athick rigid layer of a TPO resin forming the substrate base for thecomposite car body panel.

The size coat is preferably made from a coating composition of asolution of the CPO. The coating composition contains about 10-60% byweight of the CPO and correspondingly about 40-90% by weight of solvent.Any conventional solvent can be used that will dissolve the CPO such astoluene or xylene. The CPO preferably is a chlorinated polypropylene orchlorinated polyethylene containing up to about 50% by weight chlorineand preferably about 15-50% by weight chlorine. One preferredchlorinated polypropylene is a propylene/maleic anhydride copolymerchlorinated to a level of about 15-50% by weight chlorine. Oneparticularly preferred chlorinated polypropylene comprises polypropyleneand maleic acid containing about 18-35% by weight chlorine and having anacid no. of about 15.

The flexible backing sheet and the rigid substrate layer of thecomposite car body panel are prepared from standard automotive qualityTPO resins, typically a polypropylene resin.

The TPO composite of this invention provides automotive manufacturerswith many advantages over prior art compositions. Adhesion problems withrecessed portions of a part are minimized, solvent emissions associatedwith spray painting, the need for expensive hangers and jigs to maintainshape of a plastic part during baking, and the need for a primer whichis required in a conventional paint spraying process all are eliminated.Additionally, the composite has a unique set of characteristics thatmake it superior to conventional injection molded and spray paintedparts.

The color coat/clear coat of the composite of this invention can becured at temperatures in excess of 200° C. versus a maximum of 125° C.for conventional injection molded and spray painted plastic parts. Thisallows for the use of paint chemistries which cannot be used withconventional TPO parts. For example, the fluorocarbon polymers of thisinvention can be used and are substantially more durable and chemicalresistant than conventional low bake paints.

The TPO used for the flexible backing sheet can be of a differentquality than the TPO used for the rigid substrate layer of thecomposite. Presently, in the formation of injection molded automotiveparts from TPO resins, the TPO resin must be of the highest quality,i.e., free of gel particles and any foreign matter, to ensure that adefect free part is formed with an automotive quality surface. Since thesurface quality of the composite of this invention is determined by thesurface of the flexible backing sheet, only the backing sheet need be ofa high quality TPO resin, while the rigid substrate layer of thecomposite can be of a lower quality TPO resin, for example, that maycontain gel particles and not affect the appearance of the resultingpart or the structural integrity of the part.

The ability to separate the surface characteristic of the composite fromthe injection molded resin used to form the rigid layer of the compositeallows for the formation of greatly improved auto parts. For example,fiberglass reinforced or other filler reinforced TPO's can be used forthe injection molding resin for the rigid layer of the composite, andstronger and more rigid parts can be formed than has been possiblebefore.

The following example illustrates use of the TPO composite structure ina car body panel.

EXAMPLE 13

A thermoformed thermoplastic polyolefin (TPO) quarter panel for aPontiac Fiero having an exterior high gloss jet black automotive paintwas formed. The paint coat was first coated onto a surface of a sheet offlexible polyester film. The film is a 50 micron thick high gloss duPontMylar 200A polyester film. The paint layers coated onto the film were aclear coat, a color coat and a chlorinated polyolefin size coat. Eachwas coated onto the polyester film in that order.

A clear coating composition was prepared as follows:

    ______________________________________                                        Ingredient             Parts                                                  ______________________________________                                        Methylethyl ketone     40.85                                                  Butyrolactone          40.85                                                  Elvacite 2021 - (Polymethyl                                                                          6.22                                                   methacrylate having a weight                                                  average MW of 200,000)                                                        UV absorber  Tinuvin 900-2-hydroxy-                                                                  0.35                                                   3,5-di 1,1-dimethyl(benzyl)phenyl!-                                           2H-benzotriazole!                                                             Hindered amine light stabilizer-                                                                     0.18                                                    Tinuvin 292-bis(1,2,2,6,6-penta-                                             methyl-4 piperidinyl)sebacate!                                                Kynar 301F             1l.15                                                  ______________________________________                                    

The solid ingredients were added to the methyl ethyl ketone andbutyrolactone solvents with mixing and mixing was continued untildissolved. The film forming binder of the coating contained about 65%PVDF and 35% polymethyl methacrylate. The clear coating was applied byreverse roll coater to the polyester film. The clear coat was dried onthe polyester film by passing it through a multi-zone impinging airdrying oven having three heating zones spaced apart axially along thelength of the carrier, with each drying zone having a progressivelyhigher temperature. The clear-coated polyester sheet was passed throughthe heating zones at a line speed of about 7.5 meters per minute; eachheating zone was about 12 meters long. Temperatures of the three heatingzones were: Zone 1: 125° C.; Zone 2: 165° C.; Zone 4: 200° C. By passingthe clear coated polyester sheet through the three heating zones,substantially all solvent gases from the clear coat were removed toproduce a dry clear coat of uniform film thickness about 20 micronsthick.

A jet black color coating composition was formulated as follows:

    ______________________________________                                        Ingredient             Parts                                                  ______________________________________                                        Cyclohexanone          9.27                                                   Diisobutyl ketone      18.54                                                  Butyrolactone          8.34                                                   Elvacite 2042 = (polyethyl methacrylate                                                              10.02                                                  having a weight average MW 300,000)                                           Solsperse 17,000 Dispersing agent                                                                    0.10                                                   Kynar 301F             24.04                                                  Butyrolactone          14.14                                                  Black Pigment Dispersion                                                                             15.00                                                  ______________________________________                                    

The black pigment dispersion comprised carbon black in a vehicle ofElvacite 2043 (polyethyl methacrylate) available commercially asGibraltar 438-39110 pigment.

The color coating composition was prepared by first dissolving theacrylic resin in the cyclohexanone, disobutyl ketone and butyrolactonesolvents at a temperature of about 55° C. and then allowing it to coolbefore the polyvinyl fluoride component was added to the mixture to forma dispersion of the PVDF in the acrylic resin. The black pigmentdispersion was then added to the resulting mixture to produce the jetblack color coating composition. On a weight basis, the amount ofpigment contained in the color coating was about 4-5%. The binder of thecoating contained about 65% PVDF and 35% acrylic resin by weight. Theacrylic resin component comprised about 90% Elvacite 2042 and 10%Elvacite 2043. The color coating composition was coated onto the driedclear coat as above and then passed through the three stage ovendescribed above to dry the color coating and form a dry color coatinglayer about 20 microns thick.

A CPO (chlorinated polyolefin) size coating composition for use with aTPO backing sheet was formulated as follows:

    ______________________________________                                        Ingredient             Parts                                                  ______________________________________                                        Xylene                 24.60                                                  Chlorinated polyolefin (CPO) solution                                                                25.00                                                  (Eastman's CP-343-1 25% solids in xylene                                      of chlorinated polypropylene/maleic acid                                      polymer, acid no. about 15, chlorine                                          content about 18-23%)                                                         Toluene                42.50                                                  N-methyl pyrrolidone   1.00                                                   Acrylic Dispersion Resin                                                                             6.90                                                   (60% solids of an acrylic                                                     vinyl oxazoline ester polymer                                                 described in Example 1 of Miller                                              U.S. Pat. No. 3,844,993)                                                      ______________________________________                                    

The binder of the size coating composition contained about 60% CPO andabout 40% acrylic resin by weight. The size coat composition was coatedonto the dried color coat to a dry film thickness of about 2.5 micronsusing the reverse roll coater. The three temperature zones weremaintained at the same temperature as used for the clear and color coatsbut a carrier speed 30 meters per minute was used.

The resulting paint coated polyester film was then passed to alaminating operation illustrated in FIG. 2, where the paint coat of thepolyester film was transferred to a 500 micron thick TPO backing sheetmade from RPI E-1000, thermoplastic olefinic elastomer from RepublicPlastics Company, to form a face sheet. RPI E-1000 has a flexuralmodulus of approximately 690 MPa and a melt flow rate of approximately0,8 g/10 min. In the laminating operation, the backing sheet and thepaint coated polyester film carrier were run at a lineal speed of 5meters per minute, and the laminating drum was operated at a temperatureof 177° C. The CPO size coat was heat activated and the paint coat wastransferred from the polyester film to the face of the TPO backing sheetduring the laminating operation, in which the hot steel drum applied aforce of about 54 kg/lineal cm to form the face sheet. The polyesterfilm was stripped away from the surface of the face sheet, leaving thepaint coat bonded to the TPO sheet, with the clear coat providing a highgloss surface on the exterior of the TPO backing sheet.

The resulting face sheet was then thermoformed into a complexthree-dimension shape to form a plastic quarter panel molding. In thethermoforming process, the face sheet was first heated to a temperatureof about 121° C. to soften the face sheet. The heated face sheet thenwas placed over a pressure assist vacuum former buck and a vacuum wasdrawn against the buck on the TPO side of the face sheet and 2.1 kg/cm²gauge of air pressure applied on the clear coat side of the laminate toform the heated face sheet into the three dimensional shape of thequarter panel.

The resulting thermoformed laminate was then trimmed to fit in the moldcavity of a plastic injection molding machine. A quarter panel was thenformed. An elastomeric thermoplastic alloy molding resin RTA-3263 fromRepublic Plastics Company, having a flexural modulus of about 1725 MPawas used for forming the base of the quarter panel. The resin wasinjected into the mold behind the thermoformed laminate, fusing theresin to the TPO base of the laminate to form the quarter panel about2.5-3.75 mm thick. The mold was operated at the normal melt temperaturefor the resin. A quarter panel was formed that is in an integral plasticcomposite part with a defect-free paint coat on the exterior surface ofthe panel.

The quarter panel was tested and the tests demonstrated the usefulnessof the paint coat as an exterior automotive finish. The test resultsindicated that desirable appearance properties, including gloss, wereproduced. Specular reflectance measured units 70 units at 20° gloss andDOI measured 85 units. Color uniformity was good. The test results alsodemonstrated a desirable combination of durability properties. The testpanel passed tests for gasoline resistance, acid resistance, chipresistance (gravelometer reading of 9), impact resistance (80 in./lb.for Gardner Test), and passed QUV and 96 hour humidity exposure tests.

Water Soluble Protective Coatings

As disclosed previously, a thin film of wax can be coated onto theflexible carrier sheet prior to casting the clear coat onto the carrier.The wax film can serve as a protective layer for the finished paintedcar body panel.

In addition, a separate water soluble protective coating can be appliedto the clear coat (or to the wax film on the clear coat) duringprocessing so that the water soluble layer is available to provide aprotective mar resistant exterior coating for the finished car bodypanel, through assembly of the automobile and shipment to the purchaser.The coating is preferably a low molecular weight material which adheresto the clear coat throughout processing and can be buffed to a glossyfinish.

Preferably, the water soluble protective coating is overstamped as abarrier film onto the dried clear coat. The clear coat and color coatare cast on a polyester carrier film and bonded to the flexible backingsheet as described previously. Separately, a water soluble coating suchas polyvinyl alcohol (PVA) is coated onto a flexible polyester carriersheet and dried. After the carrier film is stripped away from thesurface of the clear coat, the PVA film is overstamped onto the surfaceof the clear coat, preferably by pressure roll techniques. The PVA isseparately cast so that it is not subjected to solvent attack from theclear coat and so that it would not interfere with the transfer of glossto the surface of the clear coat from the polyester casting film. Thepolyester carrier film is then stripped away from the PVA layer, leavinga water soluble protective film of PVA bonded to the exterior surface ofthe clear coat. The resulting backing sheet is then subjected to furtherprocessing, including thermoforming and injection-cladding, leaving afinished car body panel with the water soluble protective outer coating.This coating can then be easily buffed or removed with water by the autodealer or purchaser.

Controlled Flop/Head-on Brightness

The color coats used in this process can include metallic flakepigments. When a metallic flake pigment dries on a substrate surface,the flakes generally become oriented in parallel to the surface of thesubstrate. These orientations can vary, however, especially with spraypainting, which can cause substantial disorientation and resultingdifferences in the apparent color of the finished paint. Visual colorcomparisons of metallic paints can be made by known procedures formeasuring such parameters as flop index and head-on brightness (HOB).(These measurements are described in U.S. Pat. No. 4,692,481 to Kelly,which is incorporated herein by this reference.) A finished paint coatwith well-oriented metallic flakes has desirable high flop and HOBvalues. The process of this invention can be used to produce a finishedmetallic flake paint coat with high flop and HOB values. The metallicflake color coat can be coated separately onto its polyester carrierfilm and slowly dried on the film to carefully align the metallic flakesin a parallel orientation, achieving high flop and HOB values. Thepre-aligned metallic flake pigment is then subjected to furtherprocessing (transfer to the backing sheet, thermoforming, andinjection-cladding, for example) to produce a finished car body panelwith the high flop and HOB values. The linear orientation of the flakesis not disrupted during further processing and is thought to be enhancedby the elongation occurring during thermoforming. The high values forflop and HOB are substantially higher than with spray painting a similarsubstrate.

In addition, even higher HOB values are produced when the paint coat ofthis invention uses metallic flakes with a thickness of less than about2000 Angstroms. An example of these flakes is available from AveryDecorative Film Division of Avery International. These metallic flakesare sold as L-53520 and identified as Bright Aluminum Flake. The paintcoat of this invention, when using these metallic flakes, can achieve anHOB value of greater than 140 units, for a pure silver color coat.

Pigmented Backing Sheet

Improvements can be provided by using a pigmented backing sheet in theprocess of this invention. Experiments have shown that lighttransmission through a paint-coated laminate is reduced when a pigmentedbacking sheet is used in the process, as compared with a clear backingsheet. These experiments included measuring light transmission through awhite paint coat laminated to a black backing sheet (the paint coatcomprised a clear coat and underlying white color coat), compared withmeasuring light transmission through the same white paint coat laminatedto a clear backing sheet. The pigmented backing sheet increases opacitysubstantially, thereby reducing the amount of pigment required in thecolor coat to hide defects in the underlying substrate.

Pre-Applied Graphics

Printed graphics can be incorporated into the process of this invention.In one process for applying graphics to the finished paint coat, theclear coat is first cast onto the flexible polyester carrier film. Theclear coat is then dried on its carrier film. The graphics pattern isthen printed on the surface of the dried clear coat opposite from thecarrier film. The graphics pattern can be any desired pinstripingpattern, for example. The color coat also is cast on the clear coat andover the graphics pattern and dried. This leaves the clear coat on itscarrier film with the pre-applied graphics and color coat visiblethrough the clear coat. Alternatively, the color coat can be cast in aseparate carrier film and then transferred in dry film form over thepre-printed graphics pattern and onto the dried clear coat. A suitablesize coat is then applied to the surface of the dried color coat, andthe resulting laminate is transferred to the flexible backing sheet bythe techniques described previously. The carrier film is stripped awayin this process, and the resulting paint-coated laminate is thermoformedinto the desired shape to form a mold insert. The resulting mold insertis then injection clad with the desired substrate material to form thefinished car body panel. An advantage of this process is that graphicspatterns are printed under an automotive quality clear coat, whichprovides a smooth exterior surface on the finished car body panelprotecting the underlying graphics. The graphics are therefore notsubject to wax or dirt build-up around them as is the case presentlywith graphics applied to the surface of a finished exterior paint coat.

Thus, the present invention provides a dry paint process and paintsystem which produce a useful blend of durability, chemical and visualappearance properties. The paint coat has a combination of durability,gloss, resistance to deglossing, and elongation that produce and retainexterior automotive properties in the paint coat throughout theprocessing steps. As one advantage, the invention makes it possible touse high molecular weight PVDF in an OEM exterior paint for plastic carbodies, despite the temperature limitations of molded plastic materialsand the fact that PVDF normally requires use of strong solvents and hightemperatures to form glossy films from this polymer. By alloying PVDFpolymers with acrylic polymers, the result is a paint coat with superiormechanical properties, including exterior durability, chemicalresistance and toughness. The low surface energy surfaces characteristicof fluoropolymers also provide enhanced washability and produce a highcontact angle "beading" surface requiring little or no waxing. As afurther advantage, the dry paint process allows part production andcoating to be coincidental with the other manufacturing operations at anautomobile production plant by transferring quality control, solventemission problems and color control to an outside supplier. This caneliminate from the auto plant the conventional coating operations,including application lines and ovens.

As a further advantage, the dry paint process can be extended toproducing a flexible self-adhesive laminate for use in automotiverefinishing. FIG. 14 illustrates one embodiment of such a laminate 140which can allow rapid refinishing of an exterior automotive paint coatwith greatly reduced surface preparation requirements. The flexiblelaminate comprises a removable masking 141, the clear coat 45 bonded tothe color coat 46 (although a single paint coat having exteriorautomotive properties can be used as an alternative to the separateclear coat and color coat), a flexible backing 142 adhered to the colorcoat 46, a pressure-sensitive adhesive 144 on the flexible backing, anda release backing 146 covering the pressure-sensitive adhesive. Thislaminate can be tolerant to rough surfaces and develop good adhesionbecause of the conformability provided by its flexibility and thepressure-sensitive adhesive backing. By applying a trimmableself-adhesive sheet for large and small areas, it can have applicationto skilled refinishers as well as use for the consumer market byeliminating the need for large paint booths and ovens, capitalinvestment, and environmental emission problems normally associated withexterior automotive refinishing.

Although the invention has been described as relating to automotivequality paint coats applied to car body panels, it is to be understoodthat the invention is not limited solely to automotive uses or exteriorautomotive panels. The invention is also applicable to other vehiclesrequiring automotive-quality exterior paint coats. Trucks, motorcycles,boats, dune buggies, and the like are examples. Moreover, the inventionis applicable to a variety of exterior body members or parts of motorvehicles. Bumpers, fender extensions, wheel covers, hub caps, trim ringsfor wheels, lamp housings, grills and other exterior facia components orparts are examples of other substrates to which the paint coat can beapplied, in addition to conventional exterior body parts or panels ofthe vehicle.

What is claimed is:
 1. A shaped exterior automotive body part having acontoured decorative outer surface, comprising a supporting substratesheet and a decorative transfer film bonded to one side of saidsubstrate sheet and conforming to said contoured surface, saiddecorative transfer film having a clear coat/color coat exteriorautomotive paint film comprising an outer clear coat layer having aglossy, smooth outer surface, the clear coat layer formed of anoptically clear, thermoplastic and thermoformable weatherable polymericmaterial comprising an alloy of polyvinylidene fluoride (PVDF) and anacrylic resin, in which the clear coat principally contains from about50% to about 70% PVDF and from about 30% to about 50% acrylic resin, byweight of the total PVDF and acrylic resin solids present in the clearcoat material, and a pigmented color coat of automotive quality paintadhered to an inner surface of said outer clear coat layer, the colorcoat formed of a thermoplastic and thermoformable polymeric materialwith pigments distributed therein to provide a layer of color visible tothe outer surface of the automotive body part; said supporting substratesheet comprising a continuous and self-supporting thermoformablepolymeric material having contoured surface regions formed by havingthermoformed the composite of the substrate sheet and the clearcoat/color coat paint film to a finished contoured shape of theautomotive body part and in which said contoured shape is retained bysaid composite, the decorative transfer film having regions thereofwhich have been subjected to elongation during thermoforming forconforming to said contoured surface regions of the substrate sheet toprovide the outer component of a finished glossy contoured automotivebody part having an exterior automotive quality paint finish capable ofmeeting exterior automotive paint specifications, including adistinctness-of-image value of at least about 60 quantified byinstrument measurement of said value.
 2. A shaped automotive body partaccording to claim 1 in which the distinctness-of-image value ismeasured on the HunterLab Dorigon D47R-6 instrument.
 3. A shapedautomotive body part according to claim 1 in which the substrate sheetcomprises a semi-rigid thermoplastic and thermoformable polymeric sheethaving a thickness of at least about 10 mils.
 4. A shaped automotivebody part according to claim 1 in which the finished paint coat also hasa 60 degree gloss of at least about 75 gloss units.
 5. A shapedautomotive body part according to claim 1 in which the color coatcontains a dispersion of PVDF in an acrylic solution, and the color coatfurther contains flakes in the dispersion.
 6. A shaped automotive bodypart according to claim 1 wherein said clear coat comprises asubstantially molecularly unoriented liquid or solvent cast film.
 7. Ashaped automotive body part according to claim 1 wherein the color coathas metal flakes uniformly distributed therein.
 8. A shaped automotivebody part according to claim 1 in which the outer clear coat layer has adry film thickness from about 0.5 mil to about 1.5 mil.
 9. A shapedautomotive body part according to claim 1 in which the clear coat/colorcoat paint film is a thin-film form, non-self-supporting exteriorautomotive paint film.
 10. A shaped automotive body part according toclaim 9 in which the clear coat/color coat paint film has a thickness inthe range from about one to about three mils.
 11. A shaped exteriorautomotive body part having a contoured decorative outer surface,comprising a supporting substrate sheet and a decorative transfer filmbonded to one side of said substrate sheet and conforming to saidcontoured surface, said decorative transfer film having a clearcoat/color coat exterior automotive paint film comprising an outer clearcoat layer having a glossy, smooth outer surface, the clear coat layerformed of an optically clear, thermoplastic and thermoformableweatherable polymeric material, the outer clear coat material comprisinga blend of a fluoropolymer and an acrylic resin, and a pigmented colorcoat of automotive quality paint adhered to an inner surface of saidouter clear coat layer, the color coat formed of a thermoplastic andthermoformable polymeric material with pigments distributed therein toprovide a layer of color visible to the outer surface of the automotivebody part; said supporting substrate sheet comprising a continuous andself-supporting thermoformable polymeric material having contouredsurface regions formed by having thermoformed the composite of thesubstrate sheet and the clear coat/color coat paint film to a finishedcontoured shape of the automotive body part and in which said contouredshape is retained by said composite, the decorative transfer film havingregions thereof which have been subjected to elongation during saidthermoforming for conforming to said contoured regions of the substratesheet to provide the outer component of a finished glossy contoured bodypart having an exterior automotive quality paint finish capable ofmeeting exterior automotive paint specifications, including adistinctness-of-image value of at least about 60 quantified byinstrument measurement of said value.
 12. A shaped automotive body partaccording to claim 11 in which the distinctness-of-image value ismeasured on the HunterLab Dorigon D47R-6 instrument.
 13. A shapedautomotive body part according to claim 11 in which the substrate sheetcomprises a semi-rigid thermoplastic and thermoformable polymeric sheethaving a thickness of at least about 10 mils.
 14. A shaped automotivebody part according to claim 11 in which the clear coat has a 60 degreegloss of at least about 75 gloss units.
 15. A shaped automotive bodypart according to claim 11 in which the outer clear coat/color coatpaint film is a thin-film form, non-self-supporting exterior automotivepaint film.
 16. A shaped automotive body part according to claim 15 inwhich the outer clear coat/color coat paint film has a thickness in therange from about one to about three mils.
 17. A shaped automotive bodypart according to claim 11 in which the substrate sheet comprises apolyolefin polymer.
 18. A shaped automotive body part according to claim11 in which the clear coat comprises a substantially molecularlyunoriented liquid-cast film.
 19. A shaped automotive body part accordingto claim 11 in which the outer clear coat outer layer comprises a blendof polyvinylidene fluoride and an acrylic resin.
 20. A shaped automotivebody part according to claim 11 in which the color coat contains adispersion of PVDF in an acrylic solution, and the color coat furthercontains flakes in the dispersion.
 21. A shaped exterior automotive bodypart having a contoured decorative outer surface, comprising asupporting substrate sheet and a decorative transfer film bonded to oneside of said substrate sheet and conforming to said contoured surface,said decorative transfer film having a clear coat/color coat exteriorautomotive paint film comprising an outer clear coat layer having aglossy, smooth outer surface, the clear coat layer formed of anoptically clear, thermoplastic and thermoformable weatherable polymericmaterial containing a fluoropolymer resin, and a pigmented color coat ofautomotive quality paint adhered to an inner surface of said outer clearcoat layer, the color coat formed of a thermoplastic and thermoformablepolymeric material with pigments distributed therein to provide a layerof color visible to the outer surface of the automotive body part; saidsupporting substrate sheet comprising a continuous and self-supportingthermoformable polymeric material having contoured surface regionsformed by having thermoformed the composite of the substrate sheet andthe clear coat/color coat paint film to a finished contoured shape ofthe automotive body part and in which said contoured shape is retainedby said composite, the decorative transfer film having regions thereofwhich have been subjected to elongation during said thermoforming forconforming to said contoured regions of the substrate sheet to providethe outer component of a finished glossy contoured automotive body parthaving an exterior automotive quality paint finish capable of meetingexterior automotive paint specifications, including adistinctness-of-image value of at least about 60 and a 60 degree glossvalue of at least about 75 gloss units quantified by separate instrumentmeasurements of said values.
 22. A shaped automotive body part accordingto claim 21 in which the outer clear coat/color coat paint film is athin-film form, non-self-supporting exterior automotive paint film. 23.A shaped automotive body part according to claim 22 in which the outerclear coat/color coat paint film has a thickness in the range from aboutone to about three mils.
 24. A shaped automotive body part according toclaim 21 in which the outer clear coat comprises an alloy ofpolyvinylidene fluoride and an acrylic resin, and in which the colorcoat contains a dispersion of metal flakes.
 25. A shaped automotive bodypart according to claim 24 in which the substrate sheet comprises apolyolefin polymer.
 26. A shaped automotive body part according to claim21 in which the distinctness-of-image value is measured on the HunterLabDorigon D47R-6 instrument.
 27. A shaped automotive body part accordingto claim 21 in which the substrate sheet comprises a polyolefin polymer.28. A shaped automotive body part according to claim 21 in which theclear coat comprises a substantially molecularly unoriented liquid-castfilm.
 29. A shaped automotive body part according to claim 21 in whichthe color coat layer contains a dispersion of metal flakes.
 30. A shapedautomotive body part according to claim 21 in which the substrate sheetcomprises a semi-rigid thermoplastic and thermoformable polymeric sheetwith a thickness in the range from about 10 to about 40 mils.
 31. Ashaped automotive body part according to claim 21 in which the substratesheet comprises a polyolefin polymer bonded to the color coat by achlorinated polyolefin adhesive layer.
 32. A shaped automotive body partaccording to claim 21 wherein said clear coat comprises a substantiallymolecularly unoriented liquid or solvent cast film.
 33. A shapedautomotive body part according to claim 21 in which the outer clear coatlayer has a dry film thickness from about 0.5 mil to about 1.5 mils. 34.A shaped exterior automotive body part having a contoured decorativeouter surface, comprising a supporting substrate sheet and a decorativetransfer film bonded to one side of said substrate sheet and conformingto said contoured surface, said decorative transfer film having a clearcoat/color coat exterior automotive paint film comprising an outer clearcoat layer having a glossy, smooth outer surface, the clear coat layerformed of an optically clear, thermoplastic and thermoformableweatherable polymeric material, and a pigmented color coat of automotivequality paint adhered to an inner surface of said outer clear coatlayer, the color coat formed of a thermoplastic and thermoformablepolymeric material with pigments distributed therein to provide a layerof color visible to the outer surface of the automotive body part; saidsupporting substrate sheet comprising a continuous and self-supportingthermoformable polymeric material having contoured surface regionsformed by having thermoformed the composite of the substrate sheet andthe clear coat/color coat paint film to a finished contoured shape ofthe automotive body part and in which said contoured shape is retainedby said composite, the decorative transfer film having regions thereofwhich have been subjected to elongation during said thermoforming forconforming to said contoured regions of the substrate sheet to providethe outer component of a finished glossy contoured automotive body parthaving an exterior automotive quality paint finish capable of meetingexterior automotive paint specifications, including adistinctness-of-image value of at least about 60 quantified byinstrument measurement of said value.
 35. A shaped automotive body partaccording to claim 34 in which the color coat contains a dispersion ofmetal flakes.
 36. A shaped automotive body part according to claim 34 inwhich the substrate sheet comprises a polyolefin polymer.
 37. A shapedautomotive body part according to claim 34 in which thedistinctness-of-image value is measured on the HunterLab Dorigon D47R-6instrument.
 38. A shaped automotive body part according to claim 34 inwhich the substrate sheet comprises a semi-rigid thermoplastic andthermoformable polymeric sheet having a thickness of at least about 10mils.
 39. A shaped exterior automotive body part having a contoureddecorative outer surface, comprising a supporting substrate sheet and adecorative transfer film bonded to one side of said substrate sheet andconforming to said contoured surface, said decorative transfer filmhaving a clear coat/color coat exterior automotive paint film comprisingan outer clear coat layer having a glossy, smooth outer surface, theclear coat layer formed of an optically clear, thermoplastic andthermoformable weatherable polymeric material, and a pigmented colorcoat of automotive quality paint adhered to an inner surface of saidouter clear coat layer, the color coat formed of a thermoplastic andthermoformable to polymeric material with pigments distributed thereinto provide a layer of color visible to the outer surface of theautomotive body part; said supporting substrate sheet comprising acontinuous and self-supporting semi-rigid thermoformable polymeric sheethaving a thickness of at least about 20 mils and having contouredsurface regions formed by having thermoformed the composite of thesubstrate sheet and the clear coat/color coat paint film to a finishedcontoured shape of the automotive body part and in which said contouredshape is retained by said composite, the decorative transfer film havingregions thereof which have been subjected to elongation during saidthermoforming for conforming to said contoured regions of the substratesheet to provide the outer component of a finished glossy contouredautomotive body part having an exterior automotive quality paint finishcapable of meeting exterior automotive paint specifications, including adistinctness-of-image value of at least about 60 quantified byinstrument measurement of said value.
 40. A shaped automotive body partaccording to claim 39 in which the color coat contains a dispersion ofmetal flakes.
 41. A shaped automotive body part according to claim 39 inwhich the substrate sheet comprises a polyolefin polymer.
 42. A shapedautomotive body part according to claim 39 in which thedistinctness-of-image value is measured on the HunterLab Dorigon D47R-6instrument.
 43. A shaped automotive body part according to claim 39 inwhich the finished paint coat has a 60 degree gloss of at least about 75gloss units.
 44. A shaped automotive body part according to claim 39 inwhich the substrate sheet comprises a thermoplastic backing sheet.
 45. Ashaped automotive body part according to claim 44 in which the finishedpaint coat has a 60 degree gloss of at least about 75 gloss units.
 46. Ashaped automotive body part according to claim 44 in which the outerclear coat comprises an alloy of polyvinylidene fluoride (PVDF) and anacrylic resin.
 47. A shaped automotive body part according to claim 46in which the clear coat principally contains from about 50% to about 70%PVDF and from about 30% to about 50% acrylic resin, by weight of thelatest PVDF and acrylic resin solids present in the clear coat material.48. A shaped automotive body part according to claim 47 in which thecolor coat contains a dispersion of metal flakes.